<PAGE>
   
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JUNE 21, 2001
    
 
   
                                                      REGISTRATION NO. 333-61940
    
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            ------------------------
 
   
                                AMENDMENT NO. 1
                                       TO
    
 
                                    FORM S-3
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
 
                              SONUS NETWORKS, INC.
             (Exact name of registrant as specified in its charter)
                         ------------------------------
 

<TABLE>
<S>                                                           <C>
                          DELAWARE                                         04-3387074
      (State or other jurisdiction of incorporation or        (I.R.S. Employer Identification No.)
                       organization)
</TABLE>

 
                                5 CARLISLE ROAD
                         WESTFORD, MASSACHUSETTS 01886
                                 (978) 692-8999
  (Address, including zip code, and telephone number, including area code, of
                   registrant's principal executive offices)
                         ------------------------------
 
                                HASSAN M. AHMED
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                              SONUS NETWORKS, INC.
                                5 CARLISLE ROAD
                         WESTFORD, MASSACHUSETTS 01886
                                 (978) 692-8999
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)
                         ------------------------------
 
                                   COPIES TO:
 
                              DAVID L. ENGEL, ESQ.
                             JOHAN V. BRIGHAM, ESQ.
                                BINGHAM DANA LLP
                               150 FEDERAL STREET
                          BOSTON, MASSACHUSETTS 02110
                            TELEPHONE (617) 951-8000
                            TELECOPY (617) 951-8736
                         ------------------------------
 
    Approximate date of commencement of proposed sale to the public: From time
to time after the effective date of this registration statement.
 
    If the only securities being registered on this Form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. / /
 
    If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. /X/
 
    If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /  ___________________
 
    If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /  ____________________________________________________
 
   
    If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. / /
    
                         ------------------------------
 
   
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON THE DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a),
MAY DETERMINE.
    
 
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

<PAGE>
THE INFORMATION IN THIS PRELIMINARY PROSPECTUS IS NOT COMPLETE AND MAY BE
CHANGED. THESE SECURITIES MAY NOT BE SOLD UNTIL THE REGISTRATION STATEMENT FILED
WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PRELIMINARY
PROSPECTUS IS NOT AN OFFER TO SELL NOR DOES IT SEEK AN OFFER TO BUY THESE
SECURITIES IN ANY JURISDICTION WHERE THE OFFER OR SALE IS NOT PERMITTED.

<PAGE>
   
                  SUBJECT TO COMPLETION. DATED JUNE 21, 2001.
    
 
PROSPECTUS
 
                                 $1,000,000,000
 
                                     [LOGO]
 
                                 Debt Securities
                                    Warrants
                                  Common Stock
 
    We will provide the specific terms for each of these securities and their
offering prices in supplements to this prospectus. In the case of debt
securities, these terms will include, as applicable, the specific designation,
aggregate principal amount, maturity, rate or formula of interest, premium and
terms for redemption. In the case of warrants to purchase debt securities or
shares of common stock, the terms will include term, conversion and exercise
prices and other terms. In the case of common stock, these terms will include
the aggregate number of shares offered.
 
    We may sell any combination of these securities in one or more offerings up
to a total dollar amount of $1,000,000,000. We may sell these securities to or
through underwriters and also to other purchasers or through agents. We will set
forth the names of any underwriters or agents in the accompanying prospectus
supplement.
 
   
    Our common stock is listed on the Nasdaq National Market under the symbol
"SONS". None of the other securities are currently publicly traded.
    
 
   
    You should read carefully this prospectus, the documents incorporated by
reference in the prospectus and any prospectus supplement before you invest. We
strongly recommend that you read carefully the risks we describe in the
accompanying prospectus supplement, as well as the risk factors in our most
current reports to the Securities and Exchange Commission, for a fuller
understanding of the risks and uncertainties that we face.
    
 
    SEE "RISK FACTORS" ON PAGE 5 TO READ ABOUT FACTORS YOU SHOULD CONSIDER
BEFORE BUYING THESE SECURITIES.
 
    NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY OTHER REGULATORY BODY
HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE ACCURACY OR
ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL
OFFENSE.
 
    This prospectus may not be used to consummate sales of securities unless it
is accompanied by a prospectus supplement.
 
                            ------------------------
 
                              GOLDMAN, SACHS & CO.
 
                                ----------------
 
                      Prospectus dated             , 2001.

<PAGE>
                               TABLE OF CONTENTS
 
   

<TABLE>
<CAPTION>
                                                                PAGE
                                                              --------
<S>                                                           <C>
About this Prospectus.......................................      1
 
Where You Can Find More Information.........................      1
 
Incorporation by Reference..................................      1
 
Summary.....................................................      3
 
About Sonus Networks........................................      3
 
Summary of the Securities We Are Offering...................      3
 
Risk Factors................................................      5
 
Special Note Regarding Forward-Looking Statements...........      5
 
Use of Proceeds.............................................      5
 
Description of Capital Stock................................      6
 
Description of Debt Securities..............................     10
 
Description of Warrants.....................................     17
 
Plan of Distribution........................................     18
 
Legal Matters...............................................     20
 
Experts.....................................................     20
</TABLE>

    

<PAGE>
                             ABOUT THIS PROSPECTUS
 
   
    This prospectus is part of a registration statement that we filed with the
Securities and Exchange Commission, or SEC, using a "shelf" registration
process. Under this shelf process we may offer, from time to time, in one or
more offerings:
    
 
    - our debt securities;
 
    - warrants to purchase our common stock or debt securities; or
 
    - shares of our common stock.
 
   
    The total aggregate offering price of these securities will not exceed
$1,000,000,000. This prospectus provides you with a general description of the
securities we may offer. Each time we offer securities, we will provide you with
a prospectus supplement that will describe the specific amounts, prices and
terms of the securities we offer. The prospectus supplement also may add, update
or change information contained in this prospectus.
    
 
    We may sell the securities to or through underwriters, dealers or agents or
directly to purchasers. We and our agents reserve the sole right to accept and
to reject in whole or in part any proposed purchase of securities. A prospectus
supplement, which we will provide to you each time we offer securities, will
provide the names of any underwriters, dealers or agents involved in the sale of
the securities, and any applicable fee, commission or discount arrangements with
them.
 
                      WHERE YOU CAN FIND MORE INFORMATION
 
   
    We have filed with the SEC under the Securities Act of 1933 a registration
statement on Form S-3. This prospectus does not contain all of the information
contained in the registration statement since portions have been omitted under
the rules of the SEC. We also file annual, quarterly and special reports, proxy
statements and other information with the SEC under the Exchange Act. The
Exchange Act file number for our SEC filings is 000-30229. You may read and copy
the registration statement and any other document we file at the following SEC
public reference rooms:
    
 

<TABLE>
<S>                            <C>                            <C>
       Judiciary Plaza            500 West Madison Street         7 World Trade Center
   450 Fifth Street, N.W.               14th Floor                     Suite 1300
          Rm. 1024                Chicago, Illinois 60661       New York, New York 10048
   Washington, D.C. 20549
</TABLE>

 
    You may obtain information on the operation of the public reference room in
Washington, D.C. by calling the SEC at 1-800-SEC-0330. We file information
electronically with the SEC. Our SEC filings are available from the SEC's
Internet site at HTTP://WWW.SEC.GOV, which contains reports, proxy and
information statements and other information regarding issuers that file
electronically. You may read and copy our SEC filings and other information at
the offices of Nasdaq Operations, 1735 K Street, N.W., Washington, D.C. 20006.
 
                           INCORPORATION BY REFERENCE
 
    The SEC allows us to "incorporate by reference" the documents we file with
it, which means that we can disclose important information to you by referring
you to those documents instead of reproducing that information in this
prospectus. The information incorporated by reference is considered to be part
of this prospectus, and information in documents that we file later with the SEC
will automatically update and supersede information in this prospectus. We
incorporate by reference the following documents:
 
    - Our Annual Report on Form 10-K for the fiscal year ended December 31, 2000
      filed on March 28, 2001;

<PAGE>
   
    - Our Quarterly Report on Form 10-Q for the quarter ended March 31, 2001
      filed on May 15, 2001;
    
 
   
    - Our Current Report on Form 8-K filed on June 21, 2001; and
    
 
   
    - The description of common stock contained in our registration statement on
      Form 8-A filed on April 5, 2000, as amended.
    
 
    In addition to the documents listed above, we also incorporate by reference
any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d)
of the Securities Exchange Act of 1934, including any filings after the date of
initial filing and prior to the effectiveness of the registration statement of
which this propectus is a part, until we have sold all of the offered securities
to which this prospectus relates or the offering is otherwise terminated.
 
    We will provide a copy of the documents we incorporate by reference, at no
cost, to any person who receives this prospectus. To request a copy of any or
all of these documents, you should write or telephone us at: 5 Carlisle Road,
Westford, Massachusetts 01886, Attention: Investor Relations; telephone
(978) 692-8999.
 
                                       2

<PAGE>
                                    SUMMARY
 
    This summary highlights the more detailed information contained elsewhere in
this prospectus. It may not include all the information that is important to
you. You should read the entire prospectus, the prospectus supplement delivered
with the prospectus, and the documents incorporated by reference before making
an investment decision.
 
                              ABOUT SONUS NETWORKS
 
    We are a leading provider of voice infrastructure products for the new
public network. Our products are a new generation of carrier-class switching
equipment and software that enable voice services to be delivered over
packet-based networks. Designed for deployment at the core of a service
provider's network, our products significantly reduce the cost to build and
operate voice services compared to traditional alternatives. Moreover, our
products offer a powerful and open platform for service providers to increase
their revenues through the creation and delivery of new and innovative voice and
data services. Our customers include world-leading service providers. Our
objective is to capitalize on our early technology and market lead and build the
premier franchise in voice infrastructure solutions for the new public network.
 
    We were incorporated as a Delaware corporation in August 1997. Our principal
executive offices are located at 5 Carlisle Road, Westford, Massachusetts 01886,
and our telephone number is (978) 692-8999.
 
                   SUMMARY OF THE SECURITIES WE ARE OFFERING
 
    We may offer any of the following securities from time to time:
 
    - debt securities;
 
    - warrants to purchase debt securities or common stock; or
 
    - common stock.
 
   
    When we use the term "securities" in this prospectus, we mean any of the
securities we may offer with this prospectus, unless we say otherwise. The total
aggregate dollar amount of all securities that we may issue will not exceed
$1,000,000,000. If we issue debt securities at a discount from their original
stated principal amount, then, for purposes of calculating the total dollar
amount of all securities issued under this prospectus, we will treat the initial
offering price of the debt securities as the total original principal amount of
the debt securities. This prospectus, including the following summary, describes
the general terms that may apply to the securities. The specific terms of any
particular securities that we may offer will be described in a separate
supplement to this prospectus.
    
 
DEBT SECURITIES
 
   
    Our debt securities may be senior or subordinated in right of payment. For
any particular debt securities we offer, the applicable prospectus supplement
will describe the specific designation, the aggregate principal or face amount
and the purchase price; the ranking, whether senior or subordinated; the stated
maturity; the redemption terms, if any; the conversion terms, if any; the rate
or manner of calculating the rate and the payment dates for interest, if any;
the amount or manner of calculating the amount payable at maturity and whether
that amount may be paid by delivering cash, securities or other property; and
any other specific terms. We will issue the senior and subordinated debt
securities under separate indentures between us and a trustee that we will
identify in the applicable prospectus supplement.
    
 
                                       3

<PAGE>
WARRANTS
 
    We may offer warrants to purchase our debt securities or common stock. For
any particular warrants we offer, the applicable prospectus supplement will
describe the underlying security; the expiration date; the exercise price or the
manner of determining the exercise price; the amount and kind, or the manner of
determining the amount and kind, of security to be delivered by us upon
exercise; and any other specific terms. We may issue the warrants under warrant
agreements between us and one or more warrant agents.
 
COMMON STOCK
 
    We may offer shares of our common stock. Our common stock currently is
traded on the Nasdaq National Market under the symbol "SONS".
 
LISTING
 
    If any securities are to be listed or quoted on a securities exchange or
quotation system, the applicable prospectus supplement will say so.
 
                                       4

<PAGE>
                                  RISK FACTORS
 
    Investing in our securities involves a high degree of risk. Before making an
investment decision, you should carefully consider the risk factors set forth in
the accompanying prospectus supplement, our Quarterly Report on Form 10-Q for
the quarter ended March 31, 2001, filed on May 15, 2001, as well as other
information we include or incorporate by reference in this prospectus and the
additional information in the other reports we file with the SEC. The risks and
uncertainties we have described are not the only ones facing our company.
Additional risks and uncertainties not presently known to us or that we
currently deem immaterial may also affect us.
 
               SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS
 
    Some of the statements contained in this prospectus, any prospectus
supplement and the documents we incorporate by reference constitute
forward-looking statements that involve substantial risks and uncertainties. In
some cases, you can identify these statements by forward-looking words such as
"may," "will," "should," "expect," "plan," "anticipate," "believe," "estimate,"
or "continue" and variations of these words or comparable words. In addition,
any statements which refer to expectations, projections or other
characterizations of future events or circumstances are forward-looking
statements. These forward-looking statements involve known and unknown risks,
uncertainties and situations that may cause our industry's actual results, level
of activity, performance or achievements to be materially different from any
future results, levels of activity, performance or achievements expressed or
implied by these statements. The risk factors set forth in any prospectus
supplement and in the reports we file with the SEC that are incorporated by
reference in this prospectus provide examples of risks, uncertainties and events
that may cause our actual results to differ from the expectations described or
implied in our forward-looking statements.
 
    Although we believe that the expectations reflected in the forward-looking
statements are reasonable, we cannot guarantee future results, levels of
activity, performance or achievements. You should not place undue reliance on
these forward-looking statements, which apply only as of the date of this
prospectus. Except as required by law, we do not undertake to update or revise
any forward-looking statement, whether as a result of new information, future
events or otherwise.
 
                                USE OF PROCEEDS
 
    Unless we specify otherwise in a prospectus supplement, we intend to use the
net proceeds from the sales of securities to provide additional funds for our
operations and for other general corporate purposes which may include, among
other things:
 
    - the repayment of indebtedness;
 
    - working capital;
 
    - capital expenditures; and
 
    - acquisitions of, or investments in, complementary technologies or
      businesses.
 
    The precise amount and timing of the application of proceeds will depend
upon our funding requirements in the future. We may set forth additional
information on the use of net proceeds from the sale of securities we offer
under this prospectus in a prospectus supplement relating to the specific
offering.
 
                                       5

<PAGE>
                          DESCRIPTION OF CAPITAL STOCK
 
GENERAL
 
    Our authorized capital stock consists of 600,000,000 shares of common stock,
$0.001 par value per share, and 5,000,000 shares of preferred stock, $0.01 par
value per share. As of April 30, 2001, there were approximately 1,000 holders of
record of our common stock.
 
    The following description of our common stock, together with the additional
information we include in any applicable prospectus supplements, summarizes the
material terms and provisions of the common stock that we may offer under this
prospectus. For the complete terms of our common stock, please refer to our
certificate of incorporation and by-laws that are filed as exhibits to our
reports incorporated by reference into the registration statement that includes
this prospectus. Delaware's corporation law may also affect the terms of these
securities. While the terms we have summarized below will apply generally to any
future common stock that we may offer, we will describe the particular terms of
any series of these securities in more detail in the applicable prospectus
supplement, which may differ from the terms we describe below to the extent
indicated in the applicable prospectus supplement.
 
COMMON STOCK
 
    Holders of our common stock are entitled to one vote for each share held on
all matters submitted to a vote of the stockholders and do not have cumulative
voting rights. Accordingly, holders of a majority of the shares voted can elect
all of the directors then standing for election. Holders of common stock are
entitled to receive ratably any dividends that may be declared by the board of
directors out of legally available funds, subject to any preferential dividend
rights of any outstanding preferred stock. Upon our liquidation, dissolution or
winding up, the holders of common stock are entitled to receive ratably our net
assets available after the payment of all debts and other liabilities and
subject to the prior rights of any outstanding preferred stock. Holders of
common stock have no preemptive, subscription, redemption or conversion rights.
The outstanding shares of common stock are, and the shares offered in connection
with this offering will be, when issued and paid for, fully paid and
non-assessable. The rights, preferences and privileges of holders of common
stock are subject to, and may be adversely affected by, the rights of holders of
shares of any series of preferred stock that we may designate and issue in the
future without further stockholder approval.
 
PREFERRED STOCK
 
    Our board of directors is authorized without further stockholder approval to
issue from time to time up to an aggregate of 5,000,000 shares of preferred
stock in one or more series. The board of directors has discretion to fix or
alter the designations, preferences, rights, qualifications, limitations or
restrictions of the shares of each series, including the dividend rights,
dividend rates, conversion rights, voting rights, term of redemption including
sinking fund provisions, redemption price or prices, liquidation preferences and
the number of shares constituting any series or designations of any series
without further vote or action by our stockholders.
 
    The purpose of authorizing the board of directors to issue preferred stock
and determine its rights and preferences is to eliminate delays associated with
a stockholder vote on specific issuances. The issuance of preferred stock, while
providing desirable flexibility in connection with possible acquisitions and
other corporate purposes, could make it more difficult for a third party to
acquire, or could discourage a third party from acquiring, a majority of our
outstanding voting stock. We have no current plans to issue any shares of
preferred stock.
 
                                       6

<PAGE>
REGISTRATION RIGHTS
 
   
    Pursuant to the terms of an amended and restated Investors' Rights
Agreement, some holders of Sonus common stock are entitled to rights with
respect to the registration of their shares under the Securities Act. In
connection with our acquisition of telecom technologies, inc., or TTI, we have
granted additional registration rights to some former TTI stockholders. Set
forth below is a summary of the registration rights granted to these groups of
stockholders.
    
 
    RIGHTS GRANTED UNDER OUR INVESTORS' RIGHTS AGREEMENT
 
    DEMAND REGISTRATION RIGHTS.  The holders of 35% or more of the shares having
registration rights may request that we register shares of common stock. We will
be obligated to effect only two registrations pursuant to a demand request by
holders of registrable shares.
 
    We are not obligated to effect a registration 90 days prior to the
anticipated filing of, or for up to three months from the effective date of, a
company-initiated registration. We are also not required to effect a
stockholder-requested registration, if the requested registration of shares
would adversely affect, to our material harm, any other activity in which we are
then engaged. We may only delay stockholder-initiated registrations once every
twelve months.
 
    PIGGYBACK REGISTRATION RIGHTS.  Stockholders with registration rights have
unlimited rights to request that shares be included in any company-initiated
registration of common stock other than registrations of shares issued in
connection with employee benefit plans, shares issued in connection with
business combinations subject to Rule 145 under the Securities Act, convertible
debt or other specified registrations. If the registration that we initiate
involves an underwriting, however, we will not be obligated to register any
shares unless the holders agree to the terms of the underwriting agreement. It
may also be necessary, at the discretion of the lead underwriter, to limit the
number of selling stockholders in the offering, as a result of which
stockholders may only be able to register a pro rata number of registrable
shares, if any.
 
    FORM S-3 REGISTRATION RIGHTS.  We are eligible, under applicable securities
laws, to file registration statements on Form S-3. At this time, one or more
stockholders may request that we file a registration statement on Form S-3, so
long as the shares offered have an aggregate offering price of at least
$1,000,000 based on the public market price at the time of the request. We will
be obligated to effect no more than three registrations pursuant to an S-3
request by holders of registration rights.
 
   
    FUTURE GRANTS OF REGISTRATION RIGHTS.  Without the consent of current
stockholders owning at least 66 2/3% of the then-outstanding registrable shares,
we may not grant further registration rights that would be on more favorable
terms than the existing registration rights.
    
 
    TRANSFERABILITY.  The registration rights are transferable upon transfer of
registrable securities and notice by the holder to us of the transfer, provided
that, in most cases, a specified minimum number of shares, as adjusted for
splits, dividends, recapitalizations and similar events, are transferred and the
transferee or assignee assumes the rights and obligations of the transferor of
the shares.
 
    TERMINATION.  The registration rights will terminate as to any particular
registrable securities on the date on which the shares are sold pursuant to a
registration statement and are no longer subject to Rule 144 under the
Securities Act. The piggyback registration rights will expire on May 31, 2003,
the third anniversary of our initial public offering.
 
                                       7

<PAGE>
   
    RIGHTS GRANTED TO OTHER STOCKHOLDERS
    
 
   
    On January 18, 2001, we entered into a registration rights agreement with
some of the then-holders of TTI common stock. In this registration rights
agreement, we generally agree to use our reasonable best efforts to cause the
shares of our common stock held by those former holders of TTI Class A and
Class B common stock to be registered for sale under any registration statement
that we propose to file from time to time, whether on our behalf or on behalf of
our other stockholders.
    
 
DELAWARE LAW AND CHARTER AND BY-LAW PROVISIONS; ANTI-TAKEOVER EFFECTS
 
    We are subject to the provisions of Section 203 of the General Corporation
Law of Delaware. In general, the statute prohibits a publicly held Delaware
corporation from engaging in a "business combination" with an "interested
stockholder" for a period of three years after the date of the transaction in
which the person became an interested stockholder, unless the business
combination is approved in a prescribed manner. A "business combination"
includes mergers, asset sales and other transactions resulting in a financial
benefit to the interested stockholder. Subject to some exceptions, an
"interested stockholder" is a person who, together with affiliates and
associates, owns, or within three years did own, 15% or more of the
corporation's voting stock.
 
    Our amended and restated certificate of incorporation and amended and
restated by-laws provide:
 
    - that the board of directors be divided into three classes, as nearly equal
      in size as possible, with staggered three-year terms;
 
    - that directors may be removed only for cause by the affirmative vote of
      the holders of at least 66 2/3% of the shares of our capital stock
      entitled to vote; and
 
    - that any vacancy on the board of directors, however occurring, including a
      vacancy resulting from an enlargement of the board, may only be filled by
      vote of a majority of the directors then in office.
 
    The classification of the board of directors and the limitations on the
removal of directors and filling of vacancies could have the effect of making it
more difficult for a third party to acquire, or of discouraging a third party
from acquiring, Sonus.
 
    Our amended and restated certificate of incorporation and amended and
restated by-laws also provide that:
 
    - any action required or permitted to be taken by our stockholders at an
      annual meeting or special meeting of stockholders may only be taken if it
      is properly brought before the meeting and may not be taken by written
      action in lieu of a meeting; and
 
    - special meetings of our stockholders may only be called by the chairman of
      the board of directors, the president or by our board of directors.
 
    Our amended and restated by-laws provide that, in order for any matter to be
considered "properly brought" before a meeting, a stockholder must comply with
requirements regarding advance notice to us. These provisions could delay until
the next stockholders' meeting stockholder actions that are favored by the
holders of a majority of our outstanding voting securities. These provisions may
also discourage another person or entity from making a tender offer for our
common stock, because the person or entity, even if it acquired a majority of
our outstanding voting securities, would be able to take action as a
stockholder, such as electing new directors or approving a merger, only at a
duly called stockholders meeting, and not by written consent.
 
                                       8

<PAGE>
    Delaware's corporation law provides generally that the affirmative vote of a
majority of the shares entitled to vote on any matter is required to amend a
corporation's certificate of incorporation or by-laws, unless a corporation's
certificate of incorporation or by-laws, as the case may be, requires a greater
percentage. Our amended and restated certificate of incorporation requires the
affirmative vote of the holders of at least 66 2/3% of the shares of our capital
stock entitled to vote to amend or repeal any of the provisions of our amended
and restated certificate of incorporation described in the preceding paragraphs.
Generally, our amended and restated by-laws may be amended or repealed by a
majority vote of the board of directors or the holders of a majority of the
shares of our capital stock issued and outstanding and entitled to vote. To
amend our amended and restated by-laws regarding special meetings of
stockholders, written actions of stockholders in lieu of a meeting and the
election, removal and classification of members of the board of directors
requires the affirmative vote of the holders of at least 66 2/3% of the shares
of our capital stock entitled to vote. The stockholder vote would be in addition
to any separate class vote that might in the future be required pursuant to the
terms of any series of preferred stock that might be outstanding at the time any
of these amendments are submitted to stockholders.
 
LIMITATION OF LIABILITY AND INDEMNIFICATION
 
    Our amended and restated certificate of incorporation provides that our
directors and officers will be indemnified by us to the fullest extent
authorized by Delaware law. This indemnification would cover all expenses and
liabilities reasonably incurred in connection with their services for or on
behalf of us. In addition, our amended and restated certificate of incorporation
provides that our directors will not be personally liable for monetary damages
to us for breaches of their fiduciary duty as directors, unless they violated
their duty of loyalty to us or our stockholders, acted in bad faith, knowingly
or intentionally violated the law, authorized illegal dividends or redemptions
or derived an improper personal benefit from their action as directors.
 
TRANSFER AGENT AND REGISTRAR
 
    The Transfer Agent and Registrar for our common stock is American Stock
Transfer & Trust Company.
 
LISTING
 
    Our common stock is quoted on the Nasdaq National Market under the trading
symbol "SONS".
 
                                       9

<PAGE>
                         DESCRIPTION OF DEBT SECURITIES
 
    We may offer any combination of senior debt securities or subordinated debt
securities. Debt securities are unsecured obligations to repay advanced funds.
We may issue any of the senior debt securities and the subordinated debt
securities under separate indentures between us, as issuer, and the trustee or
trustees identified in a prospectus supplement. The initial forms of these
indentures are filed as exhibits to the registration statement of which this
prospectus is a part.
 
   
    The prospectus supplement will describe the particular terms of any debt
securities we may offer and these terms may differ from the terms summarized
below. The following summaries of the debt securities and certain of the
indentures are not complete. We urge you to read the indentures filed as
exhibits to the registration statement which includes this prospectus and the
description of the debt securities included in the prospectus supplement.
    
 
GENERAL
 
   
    We may issue debt securities in one or more series without limit as to
aggregate principal amount for the debt securities of any series. Unless the
prospectus supplement indicates otherwise, the debt securities will have terms
that are consistent with the indentures. Unless the prospectus supplement
indicates otherwise, senior debt securities will be unsecured and unsubordinated
obligations and will rank equal with all our other unsecured and unsubordinated
debt. Subordinated debt securities will be paid only if all payments due under
our senior indebtedness, including any outstanding senior debt securities, have
been made.
    
 
    The indentures might not limit the amount of other debt that we may incur or
whether that debt is senior to the debt securities offered by this prospectus,
and might not contain financial or similar restrictive covenants. The indentures
might not contain any provision to protect holders of debt securities against a
sudden or dramatic decline in our ability to pay our debt.
 
    The prospectus supplement will describe the debt securities and the price or
prices at which we will offer the debt securities. The description will include:
 
    - the title and form of the debt securities;
 
    - any limit on the aggregate principal amount of the debt securities or the
      series of which they are a part;
 
    - the person to whom any interest on a debt security of the series will be
      paid;
 
    - the date or dates on which we must repay the principal;
 
   
    - the rate or rates at which the debt securities will bear interest, if any,
      the date or dates from which interest will accrue, and the date or dates
      on which we must pay interest;
    
 
    - if applicable, the duration and terms of the right to extend interest
      payment periods;
 
    - the place or places where we must pay the principal and any premium or
      interest on the debt securities;
 
    - the terms and conditions on which we may redeem any debt security, if at
      all;
 
    - any obligation to redeem or purchase any debt securities, and the terms
      and conditions on which we must do so;
 
    - the denominations in which we may issue the debt securities;
 
    - the manner in which we will determine the amount of principal or any
      premium or interest on the debt securities;
 
                                       10

<PAGE>
   
    - the currency in which we will pay the principal or any premium or interest
      on the debt securities;
    
 
    - the principal amount of the debt securities that we will pay upon
      declaration of acceleration of their maturity;
 
   
    - the amount that will be deemed to be the principal amount for any purpose,
      including the principal amount that will be due and payable upon any
      maturity or that will be deemed to be outstanding as of any date;
    
 
    - if applicable, that the debt securities are defeasible and the terms of
      such defeasance;
 
    - if applicable, the terms of any right to convert debt securities into, or
      exchange debt securities for, shares of common stock or other securities
      or property;
 
    - whether we will issue the debt securities in the form of one or more
      global securities and, if so, the respective depositaries for the global
      securities and the terms of the global securities;
 
    - the subordination provisions that will apply to any subordinated debt
      securities;
 
    - any addition to or change in the events of default applicable to the debt
      securities and any change in the right of the trustee or the holders to
      declare the principal amount of any of the debt securities due and
      payable; and
 
    - any addition to or change in the covenants in the indentures.
 
    We may sell the debt securities at a substantial discount below their stated
principal amount. We will describe U.S. federal income tax considerations, if
any, applicable to debt securities sold at an original issue discount in the
prospectus supplement. An "original issue discount security" is any debt
security sold for less than its face value, and which provides that the holder
cannot receive the full face value if maturity is accelerated. The prospectus
supplement relating to any original issue discount securities will describe the
particular provisions relating to acceleration of the maturity upon the
occurrence of any event of default. In addition, we will describe U.S. federal
income tax or other considerations applicable to any debt securities that are
denominated in a currency or unit other than U.S. dollars in the prospectus
supplement.
 
CONVERSION AND EXCHANGE RIGHTS
 
    The prospectus supplement will describe, if applicable, the terms on which
the debt securities may be converted into or exchanged for common stock or other
securities or property. The conversion or exchange may be mandatory or may be at
your option. The prospectus supplement will describe how the number of shares of
common stock or other securities or property to be received upon conversion or
exchange would be calculated.
 
SUBORDINATION OF SUBORDINATED DEBT SECURITIES
 
   
    Unless the prospectus supplement indicates otherwise, the following
provisions will apply to the subordinated debt securities. The indebtedness
underlying the subordinated debt securities will be payable only if all payments
due under our senior indebtedness, including any outstanding senior debt
securities, have been made. If we distribute our assets to creditors upon any
dissolution, winding-up, liquidation or reorganization or in bankruptcy,
insolvency, receivership or similar proceedings, we must first pay all amounts
due or to become due on all senior indebtedness before we pay the principal of,
or any premium or interest on, the subordinated debt securities. In the event
the subordinated debt securities are accelerated because of an event of default,
we may not make any payment on the subordinated debt securities until we have
paid all senior indebtedness or the acceleration is rescinded. If the payment of
subordinated debt securities
    
 
                                       11

<PAGE>
   
accelerates because of an event of default, we must promptly notify holders of
senior indebtedness of the acceleration.
    
 
   
    If we experience a bankruptcy, dissolution or reorganization, holders of
senior indebtedness may recover more ratably, and holders of subordinated debt
for subordinated debt securities may recover less ratably, than our other
creditors. The indenture for subordinated debt securities may not limit our
ability to incur additional senior indebtedness.
    
 
FORM, EXCHANGE AND TRANSFER
 
    We will issue debt securities only in fully registered form, without
coupons, and, unless the prospectus supplement indicates otherwise, only in
denominations of $1,000 and integral multiples thereof. The holder of a debt
security may elect, subject to the terms of the indentures and the limitations
applicable to global securities, to exchange them for other debt securities of
the same series of any authorized denomination and of similar terms and
aggregate principal amount.
 
   
    Holders of debt securities may present them for exchange as provided above
or for registration of transfer, duly endorsed or with the form of transfer duly
executed, at the office of the transfer agent we designate for that purpose. We
will not impose a service charge for any registration of transfer or exchange of
debt securities, but we may require a payment sufficient to cover any tax or
other governmental charge payable in connection with the transfer or exchange.
We will name the transfer agent in the prospectus supplement. We may designate
additional transfer agents or rescind the designation of any transfer agent or
approve a change in the office through which any transfer agent acts, but we
must maintain a transfer agent in each place of payment on debt securities.
    
 
    If we redeem the debt securities, we will not be required to issue, register
the transfer of or exchange any debt security during a specified period prior to
mailing a notice of redemption. We are not required to register the transfer of
or exchange any debt securities selected for redemption, except the unredeemed
portion of the debt security being redeemed.
 
GLOBAL SECURITIES
 
    The debt securities may be represented, in whole or in part, by one or more
global securities that will have an aggregate principal amount equal to that of
all debt securities of that series. Each global security will be registered in
the name of a depositary identified in the prospectus supplement. We will
deposit the global security with the depositary or a custodian, and the global
security will bear a legend regarding the restrictions on exchanges and
registration of transfer.
 
   
    Unless the prospectus supplement indicates otherwise, no global security may
be exchanged in whole or in part for debt securities registered, and no transfer
of a global security in whole in part may be registered, in the name of any
person other than the depositary or any nominee or successor of the depositary
unless:
    
 
    - the depositary is unwilling or unable to continue as depositary; or
 
   
    - the depositary is no longer in good standing under the Securities Exchange
      Act of 1934 or other applicable statute or regulation.
    
 
    The depositary will determine how all securities issued in exchange for a
global security will be registered.
 
    As long as the depositary or its nominee is the registered holder of a
global security, we will consider the depositary or the nominee to be the sole
owner and holder of the global security and the underlying debt securities.
Except as stated above, owners of beneficial interests in a global security will
not be entitled to have the global security or any debt security registered in
their
 
                                       12

<PAGE>
names, will not receive physical delivery of certificated debt securities and
will not be considered to be the owners or holders of the global security or
underlying debt securities. We will make all payments of principal, premium and
interest on a global security to the depositary or its nominee. The laws of some
jurisdictions require that some purchasers of securities take physical delivery
of securities in definitive form. These laws may prevent you from transferring
your beneficial interests in a global security.
 
    Only institutions that have accounts with the depositary or its nominee and
persons that hold beneficial interests through the depositary or its nominee may
own beneficial interests in a global security. The depositary will credit, on
its book-entry registration and transfer system, the respective principal amount
of debt securities represented by the global security to the accounts of its
participants. Ownership of beneficial interests in a global security will be
shown only on, and the transfer of those ownership interests will be effected
only through, records maintained by the depositary or any such participant.
 
   
    The policies and procedures of the depositary may govern payment, transfers,
exchanges and other matters relating to beneficial interests in a global
security. We and the trustee will assume no responsibility or liability for any
aspect of the depositary's or any participant's records relating to, or for
payments made on account of, beneficial interests in a global security.
    
 
PAYMENT AND PAYING AGENTS
 
    Unless the prospectus supplement indicates otherwise, we will pay principal
and any premium or interest on a debt security to the person in whose name the
debt security is registered at the close of business on the regular record date
for the interest.
 
    Unless the prospectus supplement indicates otherwise, we will pay principal
and any premium or interest on the debt securities at the office of our
designated paying agent. Unless the prospectus supplement indicates otherwise,
the corporate trust office of the trustee will be the paying agent for the debt
securities.
 
    Any other paying agents we designate for the debt securities of a particular
series will be named in the prospectus supplement. We may designate additional
paying agents, rescind the designation of any paying agent or approve a change
in the office through which any paying agent acts, but we must maintain a paying
agent in each place of payment for the debt securities.
 
    The paying agent will return to us all money we pay to it for the payment of
the principal, premium or interest on any debt security that remains unclaimed
for a specified period. Thereafter, the holder may look only to us for payment,
as an unsecured general creditor.
 
CONSOLIDATION, MERGER AND SALE OF ASSETS
 
    Under the terms of the indentures, so long as any securities remain
outstanding, we may not consolidate or enter into a share exchange with or merge
into any other person, in a transaction in which we are not the surviving
corporation, or sell, convey, transfer or lease our properties and assets
substantially as an entirety to any person, unless:
 
    - the successor assumes our obligations under the debt securities and the
      indentures; and
 
    - we meet the other conditions described in the indentures.
 
                                       13

<PAGE>
EVENTS OF DEFAULT
 
    Each of the following will constitute an event of default under each
indenture:
 
    - failure to pay the principal of or any premium on any debt security when
      due;
 
    - failure to pay any interest on any debt security when due, for more than a
      specified number of days past the due date;
 
    - failure to deposit any sinking fund payment when due;
 
    - failure to perform any covenant or agreement in the indenture, which
      failure continued for a specified number of days after written notice has
      been given by the trustee or the requisite holders of the debt securities
      of that series;
 
    - specified events of bankruptcy, insolvency or reorganization; and
 
    - any other event of default specified in the prospectus supplement.
 
   
    If an event of default occurs and continues, both the trustee and holders of
a specified percentage in aggregate principal amount of the outstanding
securities of that series may declare the principal amount of the debt
securities of that series to be immediately due and payable. The holders of a
majority in aggregate principal amount of the outstanding securities of that
series may, under specified circumstances, rescind and annul the acceleration if
all events of default, other than the nonpayment of accelerated principal, have
been cured or waived.
    
 
    Except for specified duties in case of an event of default, the trustee will
not be obligated to exercise any of its rights or powers at the request or
direction of any of the holders, unless the holders have offered the trustee
reasonable indemnity. If they provide this indemnification, the holders of a
majority in aggregate principal amount of the outstanding securities of any
series may direct the time, method and place of conducting any proceeding for
any remedy available to the trustee or exercising any trust or power conferred
on the trustee with respect to the debt securities of that series.
 
   
    Unless the prospectus supplement indicates otherwise, no holder of a debt
security of any series may institute any proceeding with respect to the
indenture, or for the appointment of a receiver or a trustee, or for any other
remedy, unless:
    
 
    - the holder has previously given the trustee written notice of a continuing
      event of default;
 
    - the holders of a specified percentage in aggregate principal amount of the
      outstanding securities of that series have made a written request upon the
      trustee, and have offered reasonable indemnity to the trustee, to
      institute the proceeding;
 
    - the trustee has failed to institute the proceeding for a specified period
      of time after its receipt of the notification; and
 
    - the trustee has not received a direction inconsistent with the request
      within a specified number of days.
 
MODIFICATION AND WAIVER
 
   
    Unless the prospectus supplement indicates otherwise, we and the trustee may
change an indenture without the consent of any holders with respect to specific
matters, including:
    
 
    - to fix any ambiguity, defect or inconsistency in the indenture; and
 
    - to change anything that does not materially adversely affect the interests
      of any holder of debt securities of any series.
 
                                       14

<PAGE>
    In addition, under the indentures, the rights of holders of a series of debt
securities may be changed by us and the trustee, either (i) with the written
consent of the holders of not less than a majority in aggregate principal amount
of the outstanding debt securities of each class that is affected or (ii) by the
adoption of a resolution, at a meeting of holders of debt securities at which a
quorum is present, by the holders of 66 2/3% in aggregate principal amount of
the outstanding debt securities of each class that is affected represented at
such meeting. We and the trustee, however, may only make the following changes
with the consent of the holder of any outstanding debt securities affected:
 
    - extending the fixed maturity of the series of notes;
 
    - reducing the principal amount, reducing the rate of or extending the time
      of payment of interest, or any premium payable upon the redemption, of any
      debt securities; or
 
    - reducing the percentage of debt securities the holders of which are
      required to consent to any amendment.
 
   
    The holders of a majority in aggregate principal amount of the outstanding
debt securities of any series, or holders of 66 2/3% in aggregate principal
amount of such series, acting at a meeting, may waive any past default under the
indenture with respect to debt securities of that series, except a default in
the payment of principal, premium or interest on any debt security of that
series or in respect of a covenant or provision of the indenture that cannot be
amended without each holder's consent.
    
 
    Except in some limited circumstances, we may set any day as a record date
for the purpose of determining the holders of outstanding debt securities of any
series entitled to give or take any direction, notice, consent, waiver or other
action under the indentures, or be present at a meeting of holders of debt
securities. In some limited circumstances, the trustee may set a record date. To
be effective, the action must be taken by holders of the requisite principal
amount of such debt securities within a specified period following the record
date.
 
DEFEASANCE
 
    To the extent stated in the prospectus supplement, we may elect to apply the
provisions in the indentures relating to defeasance and discharge of
indebtedness, or to defeasance of some restrictive covenants, to the debt
securities of any series. The indentures provide that, upon satisfaction of the
requirements described below, we may terminate all of our obligations under the
debt securities of any series and the applicable indenture, which is known as
legal defeasance, other than our obligation:
 
    - to maintain a registrar and paying agents and hold moneys for payment in
      trust;
 
    - to register the transfer or exchange or the debt securities; and
 
    - to replace mutilated, destroyed, lost or stolen debt securities.
 
    In addition, we may terminate our obligation to comply with any restrictive
covenants under the debt securities of any series or the applicable indenture,
which is known as covenant defeasance.
 
    We may exercise our legal defeasance option even if we have previously
exercised our covenant defeasance option. If we exercise either defeasance
option, payment of the debt securities may not be accelerated because of the
occurrence of events of default.
 
    To exercise either defeasance option as to debt securities of any series, we
must irrevocably deposit in trust with the trustee money and/or obligations
backed by a full faith and credit of the United States that will provide money
in an amount sufficient in the written opinion of a national recognized firm of
independent public accountants to pay the principal of, premium, if any, and
 
                                       15

<PAGE>
each installment of interest on the debt securities. We may only establish this
trust if, among other things:
 
    - no event of default shall have occurred or be continuing;
 
    - in the case of legal defeasance, we have delivered to the trustee an
      opinion of counsel to the effect that we have received from, or there has
      been published by, the Internal Revenue Service a ruling or there has been
      a change in law, which in the opinion of our counsel, provides that
      holders of the debt securities will not recognize gain or loss for federal
      income tax purposes as a result of such deposit, defeasance and discharge
      and will be subject to federal income tax on the same amount, in the same
      manner and at the same times as would have been the case if such deposit,
      defeasance and discharge had not occurred;
 
    - in the case of covenant defeasance, we have delivered to the trustee an
      opinion of counsel to the effect that the holders of the debt securities
      will not recognize gain or loss for federal income tax purposes as a
      result of the deposit, defeasance and discharge and will be subject to
      federal income tax on the same amount, in the same manner and at the same
      times as would have been the case if the deposit, defeasance and discharge
      had not occurred; and
 
    - we satisfy other customary conditions described in the applicable
      indenture.
 
NOTICES
 
    We will mail notices to holders of debt securities as indicated in the
prospectus supplement.
 
TITLE
 
    We may treat the person in whose name a debt security is registered as the
absolute owner, whether or not such debt security may be overdue, for the
purpose of making payment and for all other purposes.
 
GOVERNING LAW
 
    The indentures and the debt securities will be governed by and construed in
accordance with the laws of the state of New York.
 
                                       16

<PAGE>
                            DESCRIPTION OF WARRANTS
 
GENERAL
 
   
    The following description, together with the additional information we may
include in any applicable prospectus supplements, summarizes the material terms
and provisions of the warrants that we may offer under this prospectus and the
related warrant agreements and warrant certificates. While the terms summarized
below will apply generally to any warrants we may offer, we will describe the
particular terms of any series of warrants in more detail in the applicable
prospectus supplement and these terms may differ from the terms described below.
    
 
    We may issue, together with other securities or separately, warrants to
purchase our debt securities or common stock. We will issue the warrants under
warrant agreements to be entered into between us and a bank or trust company, as
warrant agent, all as set forth in the applicable prospectus supplement. The
warrant agent will act solely as our agent in connection with the warrants of
the series being offered and will not assume any obligation or relationship of
agency or trust for or with any holders or beneficial owners of warrants.
 
    The applicable prospectus supplement will describe the following terms,
where applicable, of warrants in respect of which this prospectus is being
delivered:
 
    - the title of the warrants;
 
    - the designation, amount and terms of the securities for which the warrants
      are exercisable and the procedures and conditions relating to the exercise
      of such warrants;
 
    - the designation and terms of the other securities, if any, with which the
      warrants are to be issued and the number of warrants issued with each such
      security;
 
    - the price or prices at which the warrants will be issued;
 
    - the aggregate number of warrants;
 
    - any provisions for adjustment of the number or amount of securities
      receivable upon exercise of the warrants or the exercise price of the
      warrants;
 
    - the price or prices at which the securities purchasable upon exercise of
      the warrants may be purchased;
 
    - if applicable, the date on and after which the warrants and the securities
      purchasable upon exercise of the warrants will be separately transferable;
 
    - if applicable, a discussion of the material United States federal income
      tax considerations applicable to the exercise of the warrants;
 
    - any other terms of the warrants, including terms, procedures and
      limitations relating to the exchange and exercise of the warrants;
 
    - the date on which the right to exercise the warrants shall commence, and
      the date on which the right shall expire;
 
    - the maximum or minimum number of warrants which may be exercised at any
      time; and
 
    - information with respect to book-entry procedures, if any.
 
    Before exercising their warrants, holders of warrants will not have any of
the rights of holders of the securities purchasable upon such exercise,
including:
 
                                       17

<PAGE>
    - in the case of warrants to purchase debt securities, the right to receive
      payments of principal of, or premium, if any, or interest on, the debt
      securities purchasable upon exercise or to enforce covenants in the
      applicable indenture; or
 
    - in the case of warrants to purchase common stock, the right to receive
      dividends, if any, or payments upon our liquidation, dissolution or
      winding up or to exercise voting rights, if any.
 
EXERCISE OF WARRANTS
 
    Each warrant will entitle the holder thereof to purchase for cash the amount
of debt securities or shares of common stock at the exercise price as will in
each case be set forth in, or be determinable as set forth in, the applicable
prospectus supplement. Warrants may be exercised at any time up to the close of
business on the expiration date set forth in the applicable prospectus
supplement. After the close of business on the expiration date, unexercised
warrants will become void.
 
    Warrants may be exercised as set forth in the applicable prospectus
supplement relating to the warrants offered thereby. Upon receipt of payment and
the warrant certificate properly completed and duly executed at the corporate
trust office of the warrant agent or any other office indicated in the
applicable prospectus supplement, we will, as soon as practicable, forward the
purchased securities. If less than all of the warrants represented by the
warrant certificate are exercised, a new warrant certificate will be issued for
the remaining warrants.
 
ENFORCEABILITY OF RIGHTS OF HOLDERS OF WARRANTS
 
    Each warrant agent will act solely as our agent under the applicable warrant
agreement and will not assume any obligation or relationship of agency or trust
with any holder of any warrant. A single bank or trust company may act as
warrant agent for more than one issue of warrants. A warrant agent will have no
duty or responsibility in case of any default by us under the applicable warrant
agreement or warrant, including any duty or responsibility to initiate any
proceedings at law or otherwise, or to make any demand upon us. Any holder of a
warrant may, without the consent of the related warrant agent or the holder of
any other warrant, enforce by appropriate legal action its right to exercise,
and receive the securities purchasable upon exercise of, that holder's warrants.
 
                              PLAN OF DISTRIBUTION
 
    We may sell the securities being offered hereby in one or more of the
following ways from time to time:
 
    - through agents to the public or to investors;
 
    - to underwriters for resale to the public or to investors; or
 
    - directly to investors.
 
    We will set forth in a prospectus supplement the terms of the offering of
securities, including:
 
    - the name or names of any agents or underwriters;
 
    - the purchase price of the securities being offered and the proceeds that
      we will receive from the sale;
 
    - any over-allotment options under which underwriters may purchase
      additional securities from us;
 
    - any agency fees or underwriting discounts and other items constituting
      agents' or underwriters' compensation;
 
                                       18

<PAGE>
    - any initial public offering price;
 
    - any discounts or concessions allowed or reallowed or paid to dealers; and
 
    - any securities exchanges on which such securities may be listed.
 
AGENTS
 
    We may designate agents who agree to use their reasonable or best efforts to
solicit purchases for the period of their appointment or to sell securities on a
continuing basis.
 
UNDERWRITERS
 
   
    If we use underwriters for a sale of securities, the underwriters will
acquire the securities for their own account. The underwriters may resell the
securities in one or more transactions, including negotiated transactions, at a
fixed public offering price or at varying prices determined at the time of sale.
The obligations of the underwriters to purchase the securities will be subject
to the conditions set forth in the applicable underwriting agreement. The
underwriters will be obligated to purchase all the securities of the series
offered if they purchase any of the securities of that series. The underwriters
may change from time to time any initial public offering price and any discounts
or concessions the underwriters allow or reallow or pay to dealers. We may use
underwriters with whom we have a material relationship. We will describe the
nature of any such relationship in the prospectus supplement naming the
underwriter.
    
 
DIRECT SALES
 
    We may also sell securities directly to one or more purchasers without using
underwriters or agents.
 
    Underwriters, dealers and agents that participate in the distribution of the
securities may be underwriters as defined in the Securities Act and any
discounts or commissions they receive from us and any profit on their resale of
the securities may be treated as underwriting discounts and commissions under
the Securities Act. We will identify in the applicable prospectus supplement any
underwriters, dealers or agents and will describe their compensation. We may
have agreements with the underwriters, dealers and agents to indemnify them
against specified civil liabilities, including liabilities under the Securities
Act. Underwriters, dealers and agents may engage in transactions with or perform
services for us or our subsidiaries in the ordinary course of their businesses.
 
TRADING MARKETS AND LISTING OF SECURITIES
 
    Unless otherwise specified in the applicable prospectus supplement, each
class or series of securities will be a new issue with no established trading
market, other than our common stock, which is listed on the Nasdaq National
Market. We may elect to list any other class or series of securities on any
exchange, but we are not obligated to do so. It is possible that one or more
underwriters may make a market in a class or series of securities, but the
underwriters will not be obligated to do so and may discontinue any market
making at any time without notice. We cannot give any assurance as to the
liquidity of the trading market for any of the securities.
 
STABILIZATION ACTIVITIES
 
   
    Any underwriter may engage in over-allotment, stabilizing transactions,
short covering transactions and penalty bids in accordance with Regulation M
under the Securities Exchange Act of 1934. Over-allotment involves sales in
excess of the offering size, which create a short position. Stabilizing
transactions permit bids to purchase the underlying security so long as the
stabilizing
    
 
                                       19

<PAGE>
   
bids do not exceed a specified maximum. Short covering transactions involve
purchases of the securities in the open market after the distribution is
completed to cover short positions. Penalty bids permit the underwriters to
reclaim a selling concession from a dealer when the securities originally sold
by the dealer are purchased in a covering transaction to cover short positions.
Those activities may cause the price of the securities to be higher than it
would otherwise be. If commenced, the underwriters may discontinue any of the
activities at any time.
    
 
   
PASSIVE MARKET MAKING
    
 
    Any underwriters who are qualified market makers on the Nasdaq National
Market may engage in passive market making transactions in the securities on the
Nasdaq National Market in accordance with Rule 103 of Regulation M, during the
business day prior to the pricing of the offering, before the commencement of
offer or sales of the securities. Passive market makers must comply with
applicable volume and price limitations and must be identified as passive market
makers. In general, a passive market maker must display its bid at a price not
in excess of the highest independent bid for such security; if all independent
bids are lowered below the passive market maker's bid, however, the passive
market maker's bid must then be lowered when certain purchase limits are
exceeded.
 
                                 LEGAL MATTERS
 
    Bingham Dana LLP, Boston, Massachusetts, will provide us with an opinion as
to legal matters in connection with the securities we are offering.
 
                                    EXPERTS
 
   
    The consolidated financial statements of Sonus Networks, Inc. as of
December 31, 1999 and 2000, and for the years ended December 31, 1998, 1999 and
2000, incorporated by reference in this prospectus from Sonus' Annual Report on
Form 10-K for the year ended December 31, 2000, have been audited by Arthur
Andersen LLP, independent public accountants, as indicated in their report with
respect thereto, and are incorporated in reliance upon the authority of said
firm as experts in giving said report.
    
 
   
    The consolidated financial statements of telecom technologies, inc. as of
December 31, 1999 and 2000, and for the years ended December 31, 1998, 1999 and
2000, incorporated by reference in this prospectus from Sonus' Current Report on
Form 8-K filed on June 21, 2001, have been audited by Arthur Andersen LLP,
independent public accountants, as indicated in their report with respect
thereto, and are incorporated in reliance upon the authority of said firm as
experts in giving said report.
    
 
                                       20

<PAGE>

                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
   
    The following table sets forth the fees and expenses in connection with the
issuance and distribution of the securities being registered. Except for the SEC
registration fee and the NASD filing fee, all amounts are estimates.
    
 
   

<TABLE>
<CAPTION>
                                                                TOTAL
                                                              ----------
<S>                                                           <C>
SEC Registration Fee........................................  $  250,000
NASD Filing Fee.............................................      30,500
Printing and Engraving Expenses.............................      35,000
Legal Fees and Expenses.....................................      75,000
Accountants' Fees and Expenses..............................      75,000
Blue Sky Fees and Expenses..................................      15,000
                                                              ----------
  Total.....................................................  $  480,500
                                                              ==========
</TABLE>

    
 
ITEM 15. INDEMNIFICATION OF DIRECTORS, OFFICERS AND EMPLOYEES
 
    Section 145 of the Delaware General Corporation law empowers a Delaware
corporation to indemnify its officers and directors and certain other persons to
the extent and under the circumstances set forth therein.
 
    The Fourth Amended and Restated Certificate of Incorporation of the
Registrant and the Amended and Restated By-laws of the Registrant provide for
indemnification of officers and directors of the Registrant and certain other
persons against liabilities and expenses incurred by any of them in certain
stated proceedings and under certain stated conditions.
 
    The above discussion of the Registrant's Fourth Amended and Restated
Certificate of Incorporation, Amended and Restated By-Laws and Section 145 of
the Delaware General Corporation Law is not intended to be exhaustive and is
qualified in its entirety by such Fourth Amended and Restated Certificate of
Incorporation, Amended and Restated By-Laws and statute.
 
   
ITEM 16. EXHIBITS
    
 
    (a) Exhibits:
 
   

<TABLE>
<CAPTION>
       EXHIBIT
       NUMBER                                   DESCRIPTION
---------------------                           -----------
<C>                     <S>
       1.1              Form of Equity Underwriting Agreement.
 
       1.2              Form of Debt Underwriting Agreement.
 
       3.1*             Fourth Amended and Restated Certificate of Incorporation.
 
       3.2**            Certificate of Amendment to Fourth Amended and Restated
                        Certificate of Incorporation of the Registrant.
 
       3.3*             Amended and Restated By-laws of the Registrant.
 
       4.1*             Form of Common Stock Certificate.
 
       4.2              Form of Senior Debt Indenture.
 
       4.3              Form of Subordinated Debt Indenture.
</TABLE>

    
 
                                      II-1

<PAGE>
 
   

<TABLE>
<CAPTION>
       EXHIBIT
       NUMBER                                   DESCRIPTION
---------------------                           -----------
<C>                     <S>
       4.4              Form of Senior Note (included in Exhibit 4.2).
 
       4.5              Form of Subordinated Note (included in Exhibit 4.3).
 
       4.6+             Form of Warrant.
 
       5.1              Opinion of Bingham Dana LLP relating to debt securities,
                        common stock and warrants.
 
      23.1              Consent of Arthur Andersen LLP relating to the consolidated
                        financial statements of Sonus Networks, Inc.
 
      23.2              Consent of Arthur Andersen LLP relating to the consolidated
                        financial statements of telecom technologies, inc.
 
      23.3              Consent of Bingham Dana LLP (included in Exhibit 5.1).
 
      24.1++            Power of Attorney (included on signature page).
 
      25.1              Statement of Eligibility under the Trust Indenture Act of
                        1939 of a Corporation Designated to Act as Trustee on
                        Form S-1.
</TABLE>

    
 
------------------------
 
+  To be filed by amendment or as an exhibit to a report pursuant to
    Section 13(a), 13(c) or 15(d) of the Exchange Act.
 
   
++   Previously filed.
    
 
   
*   Incorporated by reference to the same-numbered exhibit to the Registrant's
    Registration Statement on Form S-1 (333-32206).
    
 
   
**  Incorporated by reference to Exhibit 99.3 to the Current Report on Form 8-K
    of the Company filed on June 21, 2001.
    
 
ITEM 17.  UNDERTAKINGS
 
    (a) The undersigned registrant hereby undertakes:
 
        (1) To file, during any period in which offers or sales are being made,
    a post-effective amendment to this registration statement:
 
           (i)  To include any prospectus required by Section 10(a)(3) of the
       Securities Act of 1933;
 
           (ii) To reflect in the prospectus any facts or events arising after
       the effective date of the Registration Statement (or the most recent
       post-effective amendment thereof) which, individually or in the
       aggregate, represent a fundamental change in the information set forth in
       the registration statement. Notwithstanding with foregoing, any increase
       or decrease in volume of securities offered (if the total dollar value of
       securities offered would not exceed that which was registered) and any
       deviation from the low or high end of the estimated maximum offering
       range may be reflected in the form of prospectus filed with the
       Commission pursuant to Rule 424(b) if, in the aggregate, the changes in
       volume and price represent no more than 20 percent change in the maximum
       aggregate offering price, set forth in the "Calculation of Registration
       Fee" table in the effective registration statement; and
 
                                      II-2

<PAGE>
           (iii) To include any material information with respect to the plan of
       distribution not previously disclosed in the registration statement or
       any material change to such information in the registration statement.
 
provided, however, that paragraphs (i) and (ii) above do not apply if the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed with or furnished to the
Commission by the registrant pursuant to Section 13 or 15(d) of the Securities
Exchange Act of 1934 that are incorporated by reference into the registration
statement.
 
        (2) That, for the purpose of determining any liability under the
    Securities Act, each such post-effective amendment shall be deemed to be a
    new registration statement relating to the securities offered therein, and
    the offering of such securities at the time shall be deemed to be the
    initial bona fide offering thereof; and
 
        (3) To remove from registration by means of a post-effective amendment
    any of the securities being registered which remain unsold at the
    termination of the offering.
 
   
    (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act (and, where applicable, each filing of an employee
benefit plan's annual report pursuant to Section 15(d) of the Exchange Act) that
is incorporated by reference in the registration statement shall be deemed to be
a new registration statement relating to the securities offered herein, and the
offering of such securities at the time shall be deemed to be the initial bona
fide offering thereof.
    
 
    (c) Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question of whether such indemnification by it is against
public policy as expressed in the Securities Act and will be governed by the
final adjudication of such issue.
 
    (d) The undersigned Registrant hereby undertakes to file an application for
the purpose of determining the eligibility of the trustee to act under
subsection (a) or Section 310 of the Trust Indenture Act in accordance with the
rules and regulations prescribed by the Commission 305(b)(2) of the Act.
 
                                      II-3

<PAGE>

                                   SIGNATURES
 
   
    Pursuant to the requirements of the Securities Act of 1933, as amended, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this registration
statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the Town of Westford, Commonwealth of Massachusetts, on this 20th
day of June, 2001.
    
 
   

<TABLE>
<S>                                                    <C>  <C>
                                                       SONUS NETWORKS, INC.
 
                                                       By:  /s/ HASSAN M. AHMED*
                                                            -----------------------------------------
                                                            Hassan M. Ahmed
                                                            PRESIDENT AND CHIEF EXECUTIVE OFFICER
</TABLE>

    
 
    Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated:
 
   

<TABLE>
<CAPTION>
               SIGNATURE                                    TITLE                         DATE
               ---------                                    -----                         ----
<C>                                      <S>                                          <C>
         /s/ HASSAN M. AHMED*            President, Chief Executive Officer and
    -------------------------------        Director (Principal Executive Officer)     June 20, 2001
            Hassan M. Ahmed
 
                                         Vice President of Finance and
          /s/ STEPHEN J. NILL              Administration, Chief Financial Officer
    -------------------------------        and Treasurer (Principal Financial and     June 20, 2001
            Stephen J. Nill                Accounting Officer)
 
           /s/ RUBIN GRUBER*             Chairman of the Board of Directors and a
    -------------------------------        Director                                   June 20, 2001
             Rubin Gruber
 
                                         Director
    -------------------------------                                                   June   , 2001
          Edward T. Anderson
 
                                         Director
    -------------------------------                                                   June   , 2001
             Paul J. Ferri
 
         /s/ PAUL J. SEVERINO*           Director
    -------------------------------                                                   June 20, 2001
           Paul J. Severino
</TABLE>

    
 
   

<TABLE>
<S>   <C>                                                    <C>                        <C>
*By:                   /s/ STEPHEN J. NILL
             --------------------------------------
                         Stephen J. Nill
                        ATTORNEY-IN-FACT
</TABLE>

    
 
                                      II-4

<PAGE>

                                 EXHIBIT INDEX
 
   

<TABLE>
<CAPTION>
       EXHIBIT
       NUMBER                                   DESCRIPTION
---------------------                           -----------
<C>                     <S>
       1.1              Form of Equity Underwriting Agreement.
 
       1.2              Form of Debt Underwriting Agreement.
 
       3.1*             Fourth Amended and Restated Certificate of Incorporation.
 
       3.2**            Certificate of Amendment to Fourth Amended and Restated
                        Certificate of Incorporation of the Registrant.
 
       3.3*             Amended and Restated By-laws of the Registrant.
 
       4.1*             Form of Common Stock Certificate.
 
       4.2              Form of Senior Debt Indenture.
 
       4.3              Form of Subordinated Debt Indenture.
 
       4.4              Form of Senior Note (included in Exhibit 4.2).
 
       4.5              Form of Subordinated Note (included in Exhibit 4.3).
 
       4.6+             Form of Warrant.
 
       5.1              Opinion of Bingham Dana LLP relating to debt securities,
                        common stock and warrants.
 
      23.1              Consent of Arthur Andersen LLP relating to the consolidated
                        financial statements of Sonus Networks, Inc.
 
      23.2              Consent of Arthur Andersen LLP relating to the consolidated
                        financial statements of telecom technologies, inc.
 
      23.3              Consent of Bingham Dana LLP (included in Exhibit 5.1).
 
      24.1++            Power of Attorney (included on signature page).
 
      25.1              Statement of Eligibility under the Trust Indenture Act of
                        1939 of a Corporation Designated to Act as Trustee on
                        Form S-1.
</TABLE>

    
 
------------------------
 
+  To be filed by amendment or as an exhibit to a report pursuant to
    Section 13(a), 13(c) or 15(d) of the Exchange Act.
 
   
++   Previously filed.
    
 
   
*   Incorporated by reference to the same-numbered exhibit to the Registrant's
    Registration Statement on Form S-1 (333-32206).
    
 
   
**  Incorporated by reference to Exhibit 99.3 to the Current Report on Form 8-K
    of the Company filed on June 21, 2001.
    





<PAGE>


                                                                     Exhibit 1.1


                              SONUS NETWORKS, INC.

                                 -------------

                     FORM OF UNDERWRITING AGREEMENT (EQUITY)


                                                                   -------, ----



Ladies and Gentlemen:

         Sonus Networks, Inc., a Delaware corporation (the "COMPANY"), proposes,
subject to the terms and conditions stated herein, to issue and sell to the
Underwriters named in Schedule I hereto (the "UNDERWRITERS") an aggregate of
__________ shares (the "FIRM SHARES") and, at the election of the Underwriters,
up to ___________ additional shares (the "OPTIONAL SHARES") of Common Stock,
$0.001 par value per share (the "STOCK"), of the Company. The Firm Shares and
the Optional Shares that the Underwriters may elect to purchase pursuant to
Section 2 hereof being collectively called the "SHARES".

The Company represents and warrants to, and agrees with, each of the
Underwriters that:

         (a) A registration statement on Form S-3 (File No. 333-_______) (the
"INITIAL REGISTRATION STATEMENT") in respect of the Shares has been filed with
the Securities and Exchange Commission (the "COMMISSION"); the Initial
Registration Statement and any post-effective amendment thereto, each in the
form heretofore delivered to you, and, excluding exhibits thereto but including
all documents incorporated by reference in the prospectus contained therein, to
you for each of the other Underwriters, have been
 declared effective by the
Commission in such form; other than a registration statement, if any, increasing
the size of the offering (a "RULE 462(b) REGISTRATION STATEMENT"), filed
pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the
"ACT"), which became effective upon filing, no other document with respect to
the Initial Registration Statement or document incorporated by reference threin
has heretofore been filed with the Commission; and no stop order suspending the
effectiveness of the Initial Registration Statement, any post-effective
amendment thereto or the Rule 462(b) Registration Statement, if any, has been
issued and no proceeding for that purpose has been initiated or threatened by
the Commission (the form of prospectus to be used in connection with the
issuance and sale of the Stock included in the Initial Registration Statement is
hereinafter called the "BASIC PROSPECTUS"; the form of prospectus supplement
included in the Initial Registration Statement is hereby called the "PROSPECTUS
Supplement"; the Basic Prospectus, as supplemented by the Prospectus Supplement,
in the form in which it shall be filed with the Commission pursuant to Rule
424(b) under the Act, is hereinafter called the


<PAGE>


"PROSPECTUS"; any preliminary prospectus included in the Initial Registration 
Statement or filed with the Commission pursuant to Rule 424(a) of the rules 
and regulations of the Commission under the Act is hereinafter called a 
"PRELIMINARY PROSPECTUS"; the various parts of the Initial Registration 
Statement and the Rule 462(b) Registration Statement, if any, including all 
exhibits thereto and including (i) the information contained in the 
Prospectus filed with the Commission pursuant to Rule 424(b) under the Act in 
accordance with Section 5(a) hereof and deemed by virtue of Rule 430A under 
the Act to be part of the Initial Registration Statement at the time it was 
declared effective and (ii) the documents incorporated by reference in the 
Prospectus contained in the Initial Registration Statement at the time such 
part of the Initial Registration Statement became effective, each as amended 
at the time such part of the Initial Registration Statement became effective 
or such part of the Rule 462(b) Registration Statement, if any, became or 
hereafter becomes effective, are hereinafter collectively called the 
"REGISTRATION STATEMENT"; any reference herein to the Registration Statement, 
Basic Prospectus, Prospectus Supplement, Preliminary Prospectus or Prospectus 
shall be deemed to refer to and include the documents incorporated by 
reference therein pursuant to Item 12 of Form S-3 under the Act, as of the 
date of such Registration Statement, Basic Prospectus, Prospectus Supplement, 
Preliminary Prospectus or Prospectus, as the case may be; any reference to 
any amendment or supplement to the Registration Statement, Basic Prospectus, 
Prospectus Supplement, Preliminary Prospectus or Prospectus shall be deemed 
to refer to and include any documents filed after the date of such 
Registration Statement, Basic Prospectus, Prospectus Supplement, Preliminary 
Prospectus or Prospectus, as the case may be, under the Securities Exchange 
Act of 1934, as amended (the "EXCHANGE ACT"), and incorporated by reference 
in such Registration Statement, Basic Prospectus, Prospectus Supplement, 
Preliminary Prospectus or Prospectus, as the case may be; and any reference 
to any amendment to the Registration Statement shall be deemed to refer to 
and include any annual report of the Company filed pursuant to Section 13(a) 
or 15(d) of the Exchange Act after the effective date of the Initial 
Registration Statement that is incorporated by reference in the Registration 
Statement);

         (b) No order preventing or suspending the use of any Preliminary
Prospectus has been issued by the Commission, and each Preliminary Prospectus,
at the time of filing thereof, conformed in all material respects to the
requirements of the Act and the rules and regulations of the Commission
thereunder, and did not contain an untrue statement of a material fact or omit
to state a material fact required to be stated therein or necessary to make the
statements therein, in the light of the circumstances under which they were
made, not misleading; PROVIDED, HOWEVER, that this representation and warranty
shall not apply to any statements or omissions made in reliance upon and in
conformity with information furnished in writing to the Company by an
Underwriter through                    expressly for use therein;

         (c) The documents incorporated by reference in the Prospectus, when
they became effective or were filed with the Commission, as the case may be,
conformed in all material respects to the requirements of the Act or the
Exchange Act, as applicable, and the rules and regulations of the Commission
thereunder, and none of such documents contained an untrue statement of a
material fact or omitted to state a material fact required to be stated therein
or necessary to make the statements therein not misleading; and any further
documents so filed and incorporated by reference in the Prospectus or any
further amendment or supplement thereto, when such documents become effective or
are filed with the Commission, as the case may be, will conform in all material
respects to the requirements of the Act or the Exchange Act, as applicable, and
the rules and regulations of the Commission thereunder and will not contain an
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements therein not misleading;
PROVIDED, HOWEVER, that this representation and warranty shall not apply to any
statements or omissions made in


                                      -2-

<PAGE>


reliance upon and in conformity with information furnished in writing to the
Company by an Underwriter through                       expressly for use
therein;

         (d) The Registration Statement conforms, and the Prospectus and any
further amendments or supplements to the Registration Statement or the
Prospectus will conform, in all material respects to the requirements of the Act
and the rules and regulations of the Commission thereunder and do not and will
not, as of the applicable effective date as to the Registration Statement and
any amendment thereto, and as of the applicable filing date as to the Prospectus
and any amendment or supplement thereto, contain an untrue statement of a
material fact or omit to state a material fact required to be stated therein or
necessary to make the statements therein not misleading; PROVIDED, HOWEVER, that
this representation and warranty shall not apply to any statements or omissions
made in reliance upon and in conformity with information furnished in writing to
the Company by an Underwriter through                     expressly for use
therein;

         (e) There are no contracts or other documents required to be described
in the Registration Statement or to be filed as exhibits to the Registration
Statement by the Act or by the rules and regulations thereunder which have not
been described or filed as required; the contracts so described in the
Prospectus to which the Company or any of its subsidiaries is a party have been
duly authorized, executed and delivered by the Company and its subsidiaries, as
are party thereto, constitute valid and binding agreements of the Company and
its subsidiaries, as are party thereto, are enforceable against the Company and
its subsidiaries, as are party thereto, in accordance with their respective
terms and are in full force and effect on the date hereof; to the best of the
Company's knowledge, the contracts so described in the Prospectus to which the
Company or any of its subsidiaries is a party are enforceable by the Company and
its subsidiaries, as are party thereto, against the other parties thereto in
accordance with their respective terms; and neither the Company nor any of its
subsidiaries, nor, to the best of the Company's knowledge, any other party is in
breach of or default under any of such contracts, except for such breaches or
defaults that, singly or in the aggregate, would not result in a material
adverse change in or affecting the business, assets, management, financial
condition or results of operations of the Company and its subsidiaries taken as
a whole;

         (f) Neither the Company nor any of its subsidiaries has sustained since
the date of the latest audited financial statements included or incorporated by
reference in the Prospectus any material loss or interference with its business
from fire, explosion, flood or other calamity, whether or not covered by
insurance, or from any labor dispute or court or governmental action, order or
decree, otherwise than as set forth in the Prospectus; and, since the respective
dates as of which information is given in the Registration Statement and the
Prospectus, there has not been any change in the capital stock (other than
issuances of Stock pursuant to Company stock option, stock incentive or stock
purchase plans described in the Registration Statement and Prospectus or in
connection with the acquisition of telecom technologies, inc. ("TTI"), as
described in the Registration Statement and Prospectus) or long-term debt (other
than as described in the Registration Statement or the Prospectus) of the
Company or any of its subsidiaries or any material adverse change, or any
development involving a prospective material adverse change, in or affecting the
business, assets, management, financial position or results of operations of the
Company and its subsidiaries taken as a whole;

         (g) None of the Company and its subsidiaries owns any real property;
each of the Company and its subsidiaries has good and marketable title to all
personal property owned by it, free and clear of all liens, encumbrances and
defects except such as are described in the


                                      -3-

<PAGE>


Prospectus or such as do not materially affect the value of such property and do
not interfere with the use made and proposed to be made of such property by the
Company and its subsidiaries; and any real property and buildings held under
lease by the Company or any of its subsidiaries are held under valid, subsisting
and enforceable leases with such exceptions as are not material and do not
interfere with the use made and proposed to be made of such property and
buildings by the Company and its subsidiaries; the Company and its subsidiaries
own or lease all such properties as are necessary to their operations as now
conducted, except where the failure to so own or lease would not, singly or in
the aggregate, result in a material adverse change in or affecting the business,
assets, management, financial condition or results of operations of the Company
and its subsidiaries taken as a whole;

         (h) Each of the Company and its subsidiaries has been duly incorporated
and is validly existing as a corporation in good standing under the laws of its
respective jurisdiction of organization, each with full power and authority
(corporate and other) to own its properties and conduct its business as
described in the Prospectus, and has been duly qualified as a foreign
corporation for the transaction of business and is in good standing under the
laws of each other jurisdiction in which it owns or leases properties or
conducts any business so as to require such qualification, or is subject to no
material liability or disability by reason of the failure to be so qualified in
any such jurisdiction;

         (i) The Company has an authorized capitalization as set forth in the
Prospectus, and all of the issued shares of capital stock of the Company have
been duly authorized and validly issued, are fully paid and non-assessable and
conform to the description of the Stock contained in the Prospectus; all of the
issued shares of capital stock of each subsidiary of the Company have been duly
authorized and validly issued, are fully paid and non-assessable and (except for
directors' qualifying shares) are owned directly or indirectly by the Company,
free and clear of all liens, encumbrances, equities or claims except such as are
described in the Prospectus; except as disclosed in or contemplated by the
Prospectus and the consolidated financial statements of the Company, and the
related notes thereto, included in the Prospectus, neither the Company nor any
subsidiary has outstanding any options to purchase, or any preemptive rights or
other rights to subscribe for or to purchase any securities or obligations
convertible into, or any contracts or commitments to issue or sell, shares of
its capital stock or any such options, rights, convertible securities or
obligations; and the description of the Company's stock option and stock
purchase plans and the options or other rights granted and exercised thereunder
set forth in the Prospectus accurately and fairly presents the information
required to be shown with respect to such plans, options and rights;

         (j) The unissued Shares to be issued and sold by the Company to the
Underwriters hereunder have been duly authorized and, when issued and delivered
against payment therefor as provided herein, will be validly issued and fully
paid and non-assessable and will conform to the description of the Stock
contained in the Prospectus; no preemptive rights or other rights to subscribe
for or purchase exist with respect to the issuance and sale of the Shares by the
Company pursuant to this Agreement; except to the extent that the exercise
thereof is contemplated by this Agreement, no stockholder of the Company has any
right, which has not been waived, to require the Company to register the sale of
any shares of capital stock owned by such stockholder under the Act in the
public offering contemplated by this Agreement; no stockholder of the Company
has any right to require the Company to register the sale of any shares of
capital stock owned by such stockholder under the Act in the 180-day period
after the date of the Prospectus other than as described in the Prospectus; and
no further approval or authority of the stockholders or the Board of Directors
of the Company will be required for the issuance and sale of the Shares to be
sold by the Company as contemplated herein;


                                      -4-

<PAGE>


         (k) The Company has full corporate power and authority to enter into
this Agreement; this Agreement has been duly authorized, executed and delivered
by the Company, constitutes a valid and binding obligation of the Company and is
enforceable against the Company in accordance with its terms;

         (l) The issue and sale of the Shares by the Company and the compliance
by the Company with all of the provisions of this Agreement and the consummation
of the transactions herein contemplated will not conflict with or result in a
breach or violation of any of the terms or provisions of, or constitute a
default under, any material indenture, mortgage, deed of trust, loan agreement
or other agreement or instrument to which the Company or any of its subsidiaries
is a party or by which the Company or any of its subsidiaries is bound or to
which any of the property or assets of the Company or any of its subsidiaries is
subject, nor will such action result in any violation of the provisions of the
Certificate of Incorporation or By-laws of the Company or any statute or any
order, rule or regulation of any court or governmental agency or body having
jurisdiction over the Company or any of its subsidiaries or any of their
properties; and no consent, approval, authorization, order, filing, registration
or qualification of or with any such court or governmental agency or body is
required for the issue and sale of the Shares or the consummation by the Company
of the transactions contemplated by this Agreement, except the registration
under the Act of the Shares and such consents, approvals, authorizations,
filings, registrations or qualifications as may be required under state
securities or Blue Sky laws in connection with the purchase and distribution of
the Shares by the Underwriters;

         (m) Except as disclosed in the Prospectus, there are no legal or
governmental actions, suits or proceedings pending or, to the best of the
Company's knowledge, threatened to which the Company or any of its subsidiaries
is or may be a party or of which property owned or leased by the Company or any
of its subsidiaries is or may be the subject, which actions, suits or
proceedings are required to be described in the Registration Statement by the
Act or the rules and regulations thereunder or which might, singly or in the
aggregate, prevent or adversely affect the transactions contemplated by this
Agreement or result in a material adverse change in or affecting the business,
assets, management, financial position (after giving effect to the offering of
the Shares) or results of operations of the Company and its subsidiaries taken
as a whole; and, to the best of the Company's knowledge, no such proceedings are
threatened or contemplated by governmental authorities or others; no labor
disturbance by the employees of the Company or any of its subsidiaries exists
or, to the knowledge of the Company, is imminent which might be expected to
affect adversely the business, assets, management, financial position or results
of operations of the Company and its subsidiaries taken as a whole; and neither
the Company nor any of its subsidiaries is a party or subject to the provisions
of any injunction, judgment, decree or order of any court, regulatory body,
administrative agency or other governmental body;

         (n) Neither the Company nor any of its subsidiaries is in violation 
of its Certificate of Incorporation or By-laws or any similar organizational 
documents or in default in the performance or observance of any obligation, 
agreement, covenant or condition contained in any indenture, mortgage, deed 
of trust, loan agreement, lease or other agreement or instrument to which it 
is a party or by which it or any of its properties may be bound except for 
such violations or defaults that would not, singly or in the aggregate, 
result in a material adverse change in or effect on the business, assets, 
management, financial position or results of operations of the Company and 
its subsidiaries taken as a whole;

         (o) The statements set forth in the Prospectus under the caption
"Description of Capital Stock", insofar as they purport to constitute a summary
of the terms of the Stock and


                                      -5-

<PAGE>


under the caption "Underwriting", insofar as they purport to describe the
provisions of the laws and documents referred to therein, are accurate, complete
and fair;

         (p) The Company is not and, after giving effect to the offering and
sale of the Shares, will not be an "investment company", as such term is defined
in the Investment Company Act of 1940, as amended (the "INVESTMENT COMPANY
ACT");

         (q) Neither the Company nor any of its affiliates does business with
the government of Cuba or with any person or affiliate located in Cuba within
the meaning of Section 517.075, Florida Statutes;

         (r) The Company and its subsidiaries possess all licenses,
certificates, authorizations or permits issued by the appropriate governmental
or regulatory agencies or authorities that are necessary to enable them to own,
lease and operate their respective properties and to carry on their respective
businesses as currently conducted and which are material to the Company and its
subsidiaries, and neither the Company nor any of its subsidiaries has received
any notice of proceedings relating to the revocation or modification of any such
license, certificate, authorization or permit which, singly or in the aggregate,
would be expected to materially and adversely affect the business, assets,
management, financial position or results of operations of the Company and its
subsidiaries taken as a whole;

         (s) The consolidated financial statements and schedules of the Company
and TTI, and the related notes thereto, included in the Registration Statement
and the Prospectus present fairly in all material respects the financial
position of the Company and TTI as of the respective dates of such financial
statements and schedules, and the results of operations and cash flows of the
Company and TTI for the respective periods covered thereby; such statements,
schedules and related notes have been prepared in accordance with generally
accepted accounting principles applied on a consistent basis as certified by the
independent public accountants named in paragraph (xx) below; no other financial
statements or schedules are required to be included in the Registration
Statement; and the selected financial data set forth in the Prospectus under the
captions "Summary Financial Information," "Capitalization" and "Selected
Financial Data" fairly present the information set forth therein on the basis
stated in the Registration Statement;

         (t) Arthur Andersen LLP, who have certified certain financial
statements of the Company and its subsidiaries, are independent public
accountants as required by the Act and the rules and regulations of the
Commission thereunder;

         (u) The Company and its subsidiaries are in compliance with any and all
applicable foreign, federal, state and local laws and regulations relating to
the protection of human health and safety, including without limitation those
relating to occupational safety and health, the environment or hazardous or
toxic substances or wastes, pollutants or contaminants, including without
limitation those relating to the storage, handling or transportation of
hazardous or toxic materials (collectively, "ENVIRONMENTAL LAWS"), except where
such noncompliance with Environmental Laws would not, singly or in the
aggregate, be expected to have a material adverse effect on the business,
assets, management, financial position or results of operations of the Company
and its subsidiaries taken as a whole. The Company, in its reasonable judgment,
has concluded that, based upon facts and circumstances existing as of the date
hereof, any costs or liabilities associated with Environmental Laws (including,
without limitation, any capital or operating expenditures required for clean-up,
closure of properties or compliance with Environmental Laws or any permit,
license or approval, any related constraints on


                                      -6-

<PAGE>


operating activities and any potential liabilities to third parties) would not,
singly or in the aggregate, reasonably be expected to have a material adverse
effect on the business, assets, management, financial position or results of
operation of the Company and its subsidiaries taken as a whole;

         (v) Except as disclosed in the Prospectus, the Company and its
subsidiaries own or have the right to use all trademarks, trade names, patent
rights, copyrights, licenses, trade secrets, know-how, intellectual property and
other similar rights necessary to conduct their business as now conducted; the
Company has no knowledge of any infringement by the Company or any of its
subsidiaries of any trademark, trade name, patent, copyright, license, trade
secret, know-how, intellectual property or other similar rights of others; and
there are no claims of infringement being made against the Company or any of its
subsidiaries regarding trademark, trade name, patent, copyright, license, trade
secret, know-how, intellectual property or other similar rights which could,
singly or in the aggregate, have a material adverse effect on the business,
assets, management, financial position or results of operations of the Company
and its subsidiaries taken as a whole; the Company has no knowledge of any
infringement by any third party of the trademark, trade name, patent, copyright,
license, trade secret, know-how, intellectual property or other similar rights
of the Company or any of its subsidiaries; none of the technology employed by
the Company or any of its subsidiaries has been obtained or is being used by the
Company or any of its subsidiaries in violation of any contractual or fiduciary
obligation binding on the Company, its subsidiaries or any of their respective
directors or executive officers or, to the best of the Company's knowledge, any
of their respective employees or consultants or otherwise in violation of the
rights of any person; none of the Company, its subsidiaries and, to the best of
the Company's knowledge, any of its employees has received any written or, to
the Company's knowledge, oral communications alleging that the Company or any of
its subsidiaries has violated or, by conducting its business as proposed, would
violate any of the intellectual property or proprietary rights of any other
person except for such violations as would not, singly or in the aggregate, have
a material adverse effect on the business, assets, management, financial
position or results of operations of the Company and its subsidiaries taken as a
whole; neither the execution nor delivery of this Agreement, nor the operation
of the business of the Company and its subsidiaries by the employees of the
Company or its subsidiaries, nor the conduct of the business of the Company and
its subsidiaries as proposed, will, to the Company's knowledge, result in a
breach or violation of the terms, conditions or provisions of, or constitute a
default under, any contract, covenant or instrument under which any of such
employees is now obligated except for such breaches, violations or defaults as
would not, singly or in the aggregate, have a material adverse effect on the
business, assets, management, financial position or results of operations of the
Company and its subsidiaries taken as a whole; and the Company and its
subsidiaries have taken and will maintain reasonable measures to prevent the
unauthorized dissemination or publication of its confidential information or the
confidential information of third parties in its possession;

         (w) The Company and each of its subsidiaries have filed all 
necessary federal, state, local and foreign income and franchise tax returns 
and have paid all taxes shown as due thereon; and the Company has no 
knowledge of any tax deficiencies which have been or might be asserted or 
threatened against the Company or any of its subsidiaries which could, singly 
or in the aggregate, materially and adversely affect the business, assets, 
management, financial position or results of operations of the Company and 
its subsidiaries taken as a whole;

         (x) Each of the Company and its subsidiaries maintains insurance of the
types and in the amounts which it reasonably deems adequate for its business,
including, but not limited to, insurance covering real and personal property
owned or leased by the Company and its


                                      -7-

<PAGE>


subsidiaries against theft, damage, destruction, acts of vandalism and all other
risks customarily insured against, all of which insurance is in full force and
effect;

         (y) Neither the Company nor any of its subsidiaries has at any time
during the last five years (i) made any unlawful contribution to any candidate
for foreign office, or failed to disclose fully any contribution in violation of
law, or (ii) made any payment to any foreign, federal or state governmental
officer or official, or other person charged with similar public or quasi-public
duties, other than payments required or permitted by the laws of the United
States or any jurisdiction thereof;

         (z) The Company has not taken and will not take, directly or indirectly
through any of its directors, officers or controlling persons, any action which
is designed to or which has constituted or which might reasonably be expected to
cause or result in stabilization or manipulation of the price of any security of
the Company to facilitate the sale or resale of the Shares; and

         (aa) The Company has filed a registration statement pursuant to Section
12(g) of the Securities Exchange Act of 1934, as amended, to register the Stock,
has filed an application to list the Stock on the National Association of
Securities Dealers Automated Quotations National Market System ("NASDAQ") and
has received notification that the listing has been approved.

2. Subject to the terms and conditions herein set forth, (a) the Company agrees
to sell to each of the Underwriters, and each of the Underwriters agrees,
severally and not jointly, to purchase from the Company, at a purchase price per
share of $_____, the number of Firm Shares (to be adjusted by you so as to
eliminate fractional shares) determined by multiplying the aggregate number of
Shares to be sold by the Company by a fraction, the numerator of which is the
aggregate number of Firm Shares to be purchased by such Underwriter set forth
opposite the name of such Underwriter in Schedule I hereto and the denominator
of which is the aggregate number of Firm Shares to be purchased by all of the
Underwriters from the Company hereunder and (b) in the event and to the extent
that the Underwriters shall exercise the election to purchase Optional Shares as
provided below, the Company agrees to sell to each of the Underwriters, and each
of the Underwriters agrees, severally and not jointly, to purchase from the
Company, at the purchase price per share set forth in clause (a) of this Section
2, that portion of the number of Optional Shares as to which such election shall
have been exercised (to be adjusted by you so as to eliminate fractional shares)
determined by multiplying the aggregate number of Optional Shares to be sold by
the Company, by a fraction, the numerator of which is the maximum number of
Optional Shares which such Underwriter is entitled to purchase as set forth
opposite the name of such Underwriter in Schedule I hereto and the denominator
of which is the maximum number of Optional Shares that all of the Underwriters
are entitled to purchase hereunder.

         The Company hereby grants to the Underwriters the right to purchase at
their election up to _________ Optional Shares, at the purchase price per share
set forth in the paragraph above, for the sole purpose of covering sales of
shares in excess of the number of Firm Shares. Any such election to purchase
Optional Shares may be exercised only by written notice from you to the Company,
given within a period of 30 calendar days after the date of this Agreement,
setting forth the aggregate number of Optional Shares to be purchased and the
date on which such Optional Shares are to be delivered, as determined by you but
in no event earlier than the First Time of Delivery (as defined in Section 4
hereof) or, unless you and the Company


                                      -8-

<PAGE>


otherwise agree in writing, earlier than two or later than ten business days
after the date of such notice.

3. Upon the authorization by you of the release of the Firm Shares, the several
Underwriters propose to offer the Firm Shares for sale upon the terms and
conditions set forth in the Prospectus.

4. (a) The Shares to be purchased by each Underwriter hereunder, in definitive
form, and in such authorized denominations and registered in such names as
                may request upon at least forty-eight hours' prior notice
to the Company shall be delivered by or on behalf of the Company to 
         , through the facilities of the Depository Trust Company ("DTC"), for
the account of such Underwriter, against payment by or on behalf of such
Underwriter of the purchase price therefor by wire transfer of Federal
(same-day) funds to the account specified by the Company to 
at least forty-eight hours in advance. The Company will cause the certificates
representing the Shares to be made available for checking and packaging at least
twenty-four hours prior to the Time of Delivery (as defined below) with respect
thereto at the office of DTC or its designated custodian (the "DESIGNATED
OFFICE"). The time and date of such delivery and payment shall be, with respect
to the Firm Shares, 9:30 a.m., New York City time, on ________, ____ or such
other time and date as                   and the Company may agree upon in
writing, and, with respect to the Optional Shares, 9:30 a.m., New York time, on
the date specified by                        in the written notice given by
                   of the Underwriters' election to purchase such Optional
Shares, or such other time and date as                    and the Company may
agree upon in writing. Such time and date for delivery of the Firm Shares is
herein called the "FIRST TIME OF DELIVERY", such time and date for delivery of
the Optional Shares, if not the First Time of Delivery, is herein called the
"SECOND TIME OF DELIVERY", and each such time and date for delivery is herein
called a "TIME OF DELIVERY".

         (b) The documents to be delivered at each Time of Delivery by or on
behalf of the parties hereto pursuant to Section 7 hereof, including the cross
receipt for the Shares and any additional documents requested by the
Underwriters pursuant to Section 7 hereof, will be delivered at the offices of
Bingham Dana LLP, Boston, Massachusetts 02110 (the "CLOSING LOCATION"), and the
Shares will be delivered at the Designated Office, all at such Time of Delivery.
A meeting will be held at the Closing Location at 6:00 p.m., New York City time,
on the New York Business Day next preceding such Time of Delivery, at which
meeting the final drafts of the documents to be delivered pursuant to the
preceding sentence will be available for review by the parties hereto. For the
purposes of this Section 4, "NEW YORK BUSINESS DAY" shall mean each Monday,
Tuesday, Wednesday, Thursday and Friday which is not a day on which banking
institutions in New York are generally authorized or obligated by law or
executive order to close.

5. The Company agrees with each of the Underwriters:

         (a) To prepare the Prospectus in a form approved by you and to file
such Prospectus pursuant to Rule 424(b) under the Act not later than the
Commission's close of business on the second business day following the
execution and delivery of this Agreement, or, if applicable, such earlier time
as may be required by Rule 430A(a)(3) under the Act; to make no further
amendment or any supplement to the Registration Statement or Prospectus prior to
the Time of Delivery which shall be disapproved by you promptly after reasonable
notice thereof; to advise you, promptly after it receives notice thereof, of the
time when any


                                      -9-

<PAGE>


amendment to the Registration Statement has been filed or becomes effective or
any supplement to the Prospectus or any amended Prospectus has been filed and to
furnish you with copies thereof; to file promptly all reports and any definitive
proxy or information statements required to be filed by the Company with the
Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act
subsequent to the date of the Prospectus and for so long as the delivery of a
prospectus is required in connection with the offering or sale of the Shares; to
advise you, promptly after it receives notice thereof, of the issuance by the
Commission of any stop order or of any order preventing or suspending the use of
any Preliminary Prospectus or the Prospectus, of the suspension of the
qualification of the Shares for offering or sale in any jurisdiction, of the
initiation or threatening of any proceeding for any such purpose, or of any
request by the Commission for the amending or supplementing of the Registration
Statement or Prospectus or for additional information; and, in the event of the
issuance of any stop order or of any order preventing or suspending the use of
any Preliminary Prospectus or the Prospectus or suspending any such
qualification, promptly to use its best efforts to obtain the withdrawal of such
order;

         (b) Promptly from time to time to take such action as you may
reasonably request to qualify the Shares for offering and sale under the
securities laws of such jurisdictions as you may reasonably request and to
comply with such laws so as to permit the continuance of sales and dealings
therein in such jurisdictions for as long as may be necessary to complete the
distribution of the Shares, provided that in connection therewith the Company
shall not be required to qualify as a foreign corporation or to file a general
consent to service of process in any jurisdiction;

         (c) Prior to 10:00 A.M., New York City time, on the New York Business
Day next succeeding the date of this Agreement and from time to time, to furnish
the Underwriters with written and electronic copies of the Prospectus in New
York City in such quantities as you may reasonably request, and, if the delivery
of a prospectus is required under the Act at any time prior to the expiration of
nine months after the time of issue of the Prospectus in connection with the
offering or sale of the Shares and if at such time any event shall have occurred
as a result of which the Prospectus as then amended or supplemented would
include an untrue statement of a material fact or omit to state any material
fact necessary in order to make the statements therein, in the light of the
circumstances under which they were made when such Prospectus is delivered, not
misleading, or, if for any other reason it shall be necessary during such period
to amend or supplement the Prospectus or to file under the Exchange Act any
document incorporated by reference in the Prospectus in order to comply with the
Act or the Exchange Act, to notify you and upon your request to file such
document and to prepare and furnish without charge to each Underwriter and to
any dealer in securities as many written and electronic copies as you may from
time to time reasonably request of an amended Prospectus or a supplement to the
Prospectus which will correct such statement or omission or effect such
compliance, and in case any Underwriter is required under the Act to deliver a
prospectus in connection with sales of any of the Shares at any time nine months
or more after the time of issue of the Prospectus, upon your request but at the
expense of such Underwriter, to prepare and deliver to such Underwriter as many
written and electronic copies as you may request of an amended or supplemented
Prospectus complying with Section 10(a)(3) of the Act;

         (d) To make generally available to its securityholders as soon as
practicable, but in any event not later than eighteen months after the effective
date of the Registration Statement (as defined in Rule 158(c) under the Act), an
earnings statement of the Company and its subsidiaries (which need not be
audited) complying with Section 11(a) of the Act and the rules and regulations
thereunder (including, at the option of the Company, Rule 158);


                                      -10-

<PAGE>


         (e) During the period beginning from the date hereof and continuing to
and including the date 90 days after the date of the Prospectus, not to offer,
sell, contract to sell or otherwise dispose of, except as provided hereunder
(including with respect to a sale of the Optional Shares) any securities of the
Company that are substantially similar to the Shares, including but not limited
to any securities that are convertible into or exchangeable for, or that
represent the right to receive, Stock or any such substantially similar
securities (other than (i) pursuant to employee stock option, stock incentive or
stock purchase plans existing on, upon the exercise of securities that represent
the right to receive Stock outstanding as of, or upon the conversion or exchange
of convertible or exchangeable securities outstanding as of, the date of this
Agreement, (ii) $[___________] aggregate principal amount of the Company's
________ Notes (the "NOTES") to be issued pursuant to the Underwriting Agreement
of even date herewith between the Company and 
                                  (the "NOTE UNDERWRITING AGREEMENT"), or 
(iii) the issuance of shares of stock from escrow in connection with the 
acquisition of TTI, as described in the Prospectus), without your prior written
consent;

         (f) To furnish to its stockholders within the time period prescribed by
the Securities Exchange Act of 1934, as amended (the "EXCHANGE ACT"), and the
rules and regulations thereunder, an annual report (including a balance sheet
and statements of income, stockholders' equity and cash flows of the Company and
its consolidated subsidiaries certified by independent public accountants) and,
within the time periods prescribed by the Exchange Act and the rules and
regulations thereunder (beginning with the fiscal quarter ending after the
effective date of the Registration Statement), to make available to its
stockholders consolidated summary financial information of the Company and its
subsidiaries for such quarter in reasonable detail;

         (g) During a period of five years from the effective date of the
Registration Statement, to furnish to you upon request copies of all reports or
other communications (financial or other) furnished to stockholders, and to
deliver to you (i) as soon as they are available, copies of any reports and
financial statements furnished to or filed with the Commission or any national
securities exchange on which any class of securities of the Company is listed;
and (ii) subject to your obligations under applicable law, such additional
information concerning the business and financial condition of the Company as
you may from time to time reasonably request (such financial statements to be on
a consolidated basis to the extent the accounts of the Company and its
subsidiaries are consolidated in reports furnished to its stockholders generally
or to the Commission);

         (h) To use the net proceeds received by it from the sale of the Shares
pursuant to this Agreement in the manner specified in the Prospectus under the
caption "Use of Proceeds" and in a manner such that the Company will not become
an "investment company" as that term is defined in the Investment Company Act;

         (i) If the Company elects to rely upon Rule 462(b), the Company shall
file a Rule 462(b) Registration Statement with the Commission in compliance with
Rule 462(b) by 10:00 P.M., Washington, D.C. time, on the date of this Agreement,
and the Company shall at the time of filing either pay to the Commission the
filing fee for the Rule 462(b) Registration Statement or give irrevocable
instructions for the payment of such fee pursuant to Rule 111(b) under the Act;

         (j) Not to grant options, warrants or other rights to purchase shares
of Stock that would become exercisable (other than in connection with a "change
of control" of the Company)


                                      -11-

<PAGE>


during the period beginning on the date hereof and continuing to and including
the date 90 days after the date of the Prospectus, other than options under the
Company's 2000 Employee Stock Purchase Plan and such options, warrants or other
rights granted to persons who, prior to such grant, execute agreements
substantially to the effect set forth in Subsection 5(e) hereof in form and
substance satisfactory to you; and

         (k) Upon request of any Underwriter to furnish, or cause to be
furnished, to such Underwriter an electronic version of the Company's
trademarks, servicemarks and corporate logo for use on the website, if any,
operated by such Underwriter for the purpose of facilitating the on-line
offering of the Shares (the "License"); PROVIDED, HOWEVER, that the License
shall be non-exclusive, shall not provide for the right to sub-license, shall be
limited solely for the purpose described above, is granted without any fee and
may not be assigned or transferred to any person and shall terminate upon
consummation of the public offering contemplated by the Prospectus.

6. The Company agrees with the several Underwriters that (a) the Company will
pay or cause to be paid the following: (i) the fees, disbursements and expenses
of the Company's counsel and accountants in connection with the registration of
the Shares under the Act and all other expenses in connection with the
preparation, printing and filing of the Registration Statement, any Preliminary
Prospectus and the Prospectus and amendments and supplements thereto and the
mailing and delivering of copies thereof to the Underwriters and dealers; (ii)
the cost of printing or producing any Agreement among Underwriters, this
Agreement, the Blue Sky Memorandum, closing documents (including any
compilations thereof) and any other documents in connection with the offering,
purchase, sale and delivery of the Shares, and the fees and disbursements of
counsel for the Underwriters in connection with securing any required review by
the National Association of Securities Dealers, Inc. of the terms of the sale of
the Shares; (iii) all expenses in connection with the qualification of the
Shares for offering and sale under state securities laws as provided in Section
5(b) hereof, including the fees and disbursements of counsel for the
Underwriters in connection with such qualification and in connection with the
Blue Sky survey; (iv) all fees and expenses in connection with listing the
Shares on the NASDAQ; (v) the filing fees incident to securing any required
review by the National Association of Securities Dealers, Inc. of the terms of
the sale of the Shares; (vi) the cost of preparing stock certificates; (vii) the
cost and charges of any transfer agent or registrar; and (viii) all other costs
and expenses incident to the performance of its obligations hereunder which are
not otherwise specifically provided for in this Section. It is understood,
however, that, (x) except as provided in this Section, and Sections 8 and 11
hereof, the Underwriters will pay all of their own costs and expenses, including
the fees of their counsel, stock transfer taxes on resale of any of the Shares
by them, and any advertising expenses connected with any offers they may make,
and (y) other than with respect to filing or similar fees, the maximum liability
of the Company under clauses (a)(ii) and (a)(iii) above shall be $20,000.

7. The obligations of the Underwriters hereunder, as to the Shares to be
delivered at each Time of Delivery, shall be subject, in their discretion, to
the condition that all representations and warranties and other statements of
the Company are, at and as of such Time of Delivery, true and correct, the
condition that the Company shall have performed all of its obligations hereunder
theretofore to be performed, and the following additional conditions:

         (a) The Prospectus shall have been filed with the Commission pursuant
to Rule 424(b) within the applicable time period prescribed for such filing by
the rules and regulations under the Act and in accordance with Section 5(a)
hereof; if the Company has elected to rely upon Rule 462(b), the Rule 462(b)
Registration Statement shall have become effective by 10:00 P.M.,


                                      -12-

<PAGE>


Washington, D.C. time, on the date of this Agreement; no stop order suspending
the effectiveness of the Registration Statement or any part thereof shall have
been issued and no proceeding for that purpose shall have been initiated or
threatened by the Commission; and all requests for additional information on the
part of the Commission shall have been complied with to your reasonable
satisfaction;

         (b)           , counsel for the Underwriters, shall have furnished to
you such written opinion or opinions (a draft of each such opinion is attached
as Annex II(a) hereto), dated such Time of Delivery, with respect to the matters
covered in paragraphs (i), (ii), (vi), (ix) and (xi) of subsection (c) below as
well as such other related matters as you may reasonably request, and such
counsel shall have received such papers and information as they may reasonably
request to enable them to pass upon such matters;

         (c) Bingham Dana LLP, counsel for the Company, shall have furnished to
you their written opinion (a draft of such opinion is attached as Annex II(b)
hereto), dated such Time of Delivery, in form and substance satisfactory to you,
to the effect that:

         (i) The Company has been duly incorporated and is validly existing as a
corporation in good standing under the laws of the State of Delaware, with
corporate power and authority to own its properties and conduct its business as
described in the Prospectus;

         (ii) The Company has an authorized capitalization as set forth in the
Prospectus; in addition: (1) all of the shares of Common Stock that were
outstanding immediately following the closing of the Company's initial public
offering on May 31, 2000, have been duly authorized and are validly issued,
fully paid and non-assessable; (2) all of the shares of Common Stock that were
issued pursuant to the Company's acquisition of TTI, which acquisition closed on
January 18, 2001, have been duly authorized and are validly issued, fully paid
and non-assessable; (3) the __________ Shares to be delivered by the Company to
the Underwriters at each Time of Delivery have been duly authorized and,
assuming due execution and delivery of this Agreement by all of the Underwriters
and compliance by all of the Underwriters with the terms thereof, and assuming
payment in full by the Underwriters for all of the Shares as provided in this
Agreement, such Shares shall be validly issued, fully paid and non-assessable;
and (4) to such counsel's knowledge, all shares of capital stock of the Company
that are, as of the date hereof, issued and outstanding, other than those shares
of capital stock described in clauses (1) through (3) of this paragraph (ii),
have been duly authorized and are validly issued, fully paid and non-assessable
and the shares conform to the summary description of the Shares contained in the
Prospectus under the caption "Description of Capital Stock;"

         (iii) The Company is duly qualified as a foreign corporation for the
transaction of business and is in good standing as a foreign corporation under
the laws of the Commonwealth of Massachusetts;

         (iv) To the best of such counsel's knowledge and other than as set
forth in the Prospectus, there are no legal or governmental proceedings pending
to which the Company or any of its subsidiaries is a party or of which any
property of the Company


                                      -13-

<PAGE>


or any of its subsidiaries is the subject which, if determined adversely to the
Company or any of its subsidiaries, would individually or in the aggregate be
reasonably expected to have a material adverse effect on the business, assets,
management, financial position or results of operations of the Company and its
subsidiaries taken as a whole; and, to such counsel's knowledge, but without
having investigated any governmental records or court dockets, no such
proceedings are overtly threatened by governmental authorities or others;

         (v) The Company has full corporate power and authority to enter into
this Agreement and this Agreement has been duly authorized, executed and
delivered by the Company;

         (vi) The issue and sale of the Shares to be delivered at such Time of
Delivery by the Company and the compliance by the Company with all of the
provisions of this Agreement and the consummation of the transactions therein
contemplated will not (a) result in a breach or violation of any of the terms or
provisions of, or constitute a default under, any indenture, mortgage, deed of
trust, loan agreement or other agreement or instrument known to such counsel to
which the Company or any of its subsidiaries is a party or by which the Company
or any of its subsidiaries is bound or to which any of the property or assets of
the Company or any of its subsidiaries is subject, (b) result in any violation
of the provisions of the Charter or By-laws or any federal or Massachusetts
statute, rule or regulation or, (c) to such counsel's knowledge, violate any
order known to such counsel of any federal or Massachusetts court or
governmental agency or body having jurisdiction over the Company or any of its
subsidiaries or any of their properties;

         (vii) No consent, approval, authorization, order, filing, registration
or qualification of or with any federal or Massachusetts court or governmental
agency or body is required for the issue and sale of the Shares or the
consummation by the Company of the transactions contemplated by this Agreement,
except the registration under the Act of the Shares, and such consents,
approvals, authorizations, filings, registrations or qualifications as may be
required under state securities or Blue Sky laws in connection with the purchase
and distribution of the Shares by the Underwriters (as to which such counsel
renders no opinion);

         (viii) The statements set forth in the Prospectus under the caption
"Description of Capital Stock," insofar as they purport to constitute a summary
of the terms of the Stock, and under the captions "Shares Eligible for Future
Sale" and "Underwriting," insofar as they purport to describe the provisions of
the laws and the underwriting agreement and lock-up agreements referred to
therein, are accurate and complete in all material respects;

         (ix) The Company is not an "investment company," as such term is
defined in the Investment Company Act and, immediately after giving effect to
the transactions contemplated by this Agreement, will not be an "investment
company;"


                                      -14-

<PAGE>


         (x) The documents incorporated by reference into the Prospectus as of
its date, or any amendment or supplement thereto made by the Company prior to
such Time of Delivery (other than the financial statements and related schedules
and other financial and accounting data therein, as to which such counsel
expresses no opinion) comply as to form in all material respects with the
requirements of the Securities Exchange Act of 1934, as amended, and the rules
and regulations thereunder;

         (xi) The Registration Statement has become effective under the Act. To
the best of such counsel's knowledge, no stop order suspending the effectiveness
of the Registration Statement has been issued by the Commission nor has any
proceeding been instituted for that purpose under the Act. The Prospectus has
been filed with the Commission pursuant to Rule 424(b) of the rules and
regulations under the Act within the time period required thereby; and

         (xii) The Registration Statement has become effective under the Act. To
the best of such counsel's knowledge, no stop order suspending the effectiveness
of the Registration Statement has been issued by the Commission nor has any
proceeding been instituted for that purpose under the Act. The Prospectus has
been filed with the Commission pursuant to Rule 424(b) of the rules and
regulations under the Act within the time period required thereby.

         (d) On the date of the Prospectus at a time prior to the execution of
this Agreement, at 9:30 a.m., New York City time, on the effective date of any
post-effective amendment to the Registration Statement filed subsequent to the
date of this Agreement and also at each Time of Delivery, Arthur Andersen LLP
shall have furnished to you a letter or letters, dated the respective dates of
delivery thereof, in form and substance satisfactory to you, to the effect set
forth in Annex I hereto (the executed copy of the letter delivered prior to the
execution of this Agreement is attached as Annex I(a) hereto and a draft of the
form of letter to be delivered on the effective date of any post-effective
amendment to the Registration Statement and as of each Time of Delivery is
attached as Annex I(b) hereto);

         (e) (i) Neither the Company nor any of its subsidiaries shall have
sustained since the date of the latest audited financial statements included or
incorporated by reference in the Prospectus any loss or interference with its
business from fire, explosion, flood or other calamity, whether or not covered
by insurance, or from any labor dispute or court or governmental action, order
or decree, otherwise than as set forth or contemplated in the Prospectus, and
(ii) since the respective dates as of which information is given in the
Prospectus there shall not have been any change in the capital stock or
long-term debt of the Company or any of its subsidiaries or any change, or any
development involving a prospective change, in or affecting the business,
assets, management, financial position, stockholders' equity or results of
operations of the Company and its subsidiaries taken as a whole, otherwise than
as set forth or contemplated in the Prospectus, the effect of which, in any such
case described in clause (i) or (ii), is in the judgment of the Representatives
so material and adverse as to make it impracticable or inadvisable to proceed
with the public offering or the delivery of the Shares being delivered at such
Time of Delivery on the terms and in the manner contemplated in the Prospectus;

         (f) On or after the date hereof there shall not have occurred any of
the following: (i) a suspension or material limitation in trading in securities
generally on the New York Stock


                                      -15-

<PAGE>


Exchange or on NASDAQ; (ii) a suspension or material limitation in trading in
the Company's securities on NASDAQ; (iii) a general moratorium on commercial
banking activities declared by either Federal or New York or Massachusetts state
authorities; or (iv) the outbreak or escalation of hostilities involving the
United States or the declaration by the United States of a national emergency or
war, if the effect of any such event specified in this clause (iv) in the
judgment of the Representatives makes it impracticable or inadvisable to proceed
with the public offering or the delivery of the Shares being delivered at such
Time of Delivery on the terms and in the manner contemplated in the Prospectus;

         (g) The Shares to be sold at such Time of Delivery shall have been duly
listed for quotation on NASDAQ;

         (h) The Company has obtained and delivered to the Underwriters executed
copies of an agreement from each of the directors, executive officers and other
stockholders of the Company listed on Schedule III hereto, in form and substance
previously agreed to by you and attached hereto as Exhibit A;

         (i) The Company shall have complied with the provisions of Section 5(c)
hereof with respect to the furnishing of prospectuses on the New York Business
Day next succeeding the date of this Agreement;

         (j) Beachcroft Wansbroughs, local counsel for Sonus Networks Limited, a
United Kingdom corporation (the "UK SUBSIDIARY"), shall have furnished to you
their written opinion (a draft of such opinion is attached as Annex II(d)
hereto), dated such Time of Delivery, in form and substance satisfactory to you,
to the effect that:

                  (i) The UK Subsidiary has been duly incorporated and is
validly existing as a corporation in good standing under the laws of the United
Kingdom; and

                  (ii) All of the issued shares of capital stock of the UK
Subsidiary have been duly authorized and validly issued, are fully paid and
nonassessable, and are owned directly or indirectly by the Company and, to the
knowledge of such counsel, free and clear of all liens, encumbrances, equities
or claims.

         (k) Singapore counsel reasonably satisfactory to the Underwriters, as
local counsel for Sonus Networks Pte Ltd, a Singapore corporation (the
"SINGAPORE SUBSIDIARY"), shall have furnished to you their written opinion (a
draft of such opinion is attached as Annex II(e) hereto), dated such Time of
Delivery, in form and substance satisfactory to you, to the effect that:

                  (i) The Singapore Subsidiary has been duly incorporated and is
validly existing as a corporation in good standing under the laws of the United
Kingdom; and

                  (ii) All of the issued shares of capital stock of the
Singapore Subsidiary have been duly authorized and validly issued, are fully
paid and nonassessable, and are owned directly or indirectly by the Company and,
to the knowledge of such counsel, free and clear of all liens, encumbrances,
equities or claims.

         (l) Texas counsel reasonably satisfactory to the Underwriters, as local
counsel for TTI, a Texas corporation, shall have furnished to you their written
opinion (a draft of such opinion is attached as Annex II(f) hereto), dated such
Time of Delivery, in form and substance satisfactory to you, to the effect that:


                                      -16-

<PAGE>


                  (i) TTI has been duly incorporated and is validly existing as
a corporation in good standing under the laws of the State of Texas; and

                  (ii) All of the issued shares of capital stock of the TTI
have been duly authorized and validly issued, are fully paid and nonassessable,
and are owned directly or indirectly by the Company and to the knowledge of 
such counsel, free and clear of all liens, encumbrances, equities or claims.

         (m) The Company shall have furnished or caused to be furnished to you
at such Time of Delivery certificates of officers of the Company satisfactory to
you as to the accuracy of the representations and warranties of the Company
herein at and as of such Time of Delivery, as to the performance by the Company
of all of its respective obligations hereunder to be performed at or prior to
such Time of Delivery, as to the matters set forth in subsections (a) and (f) of
this Section and as to such other matters as you may reasonably request.

8. (a) The Company will indemnify and hold harmless each Underwriter against any
losses, claims, damages or liabilities, joint or several, to which such
Underwriter may become subject, under the Act or otherwise, insofar as such
losses, claims, damages or liabilities (or actions in respect thereof) arise out
of or are based upon an untrue statement or alleged untrue statement of a
material fact contained in any Preliminary Prospectus, the Registration
Statement or the Prospectus, or any amendment or supplement thereto, or arise
out of or are based upon the omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, and will reimburse each Underwriter for any legal or
other expenses reasonably incurred by such Underwriter in connection with
investigating or defending any such action or claim as such expenses are
incurred; PROVIDED, HOWEVER, that the Company shall not be liable in any such
case to the extent that any such loss, claim, damage or liability arises out of
or is based upon an untrue statement or alleged untrue statement or omission or
alleged omission made in any Preliminary Prospectus, the Registration Statement
or the Prospectus or any such amendment or supplement in reliance upon and in
conformity with written information furnished to the Company by any Underwriter
through                      expressly for use therein.

         (b) Each Underwriter will indemnify and hold harmless the Company
against any losses, claims, damages or liabilities to which the Company may
become subject, under the Act or otherwise, insofar as such losses, claims,
damages or liabilities (or actions in respect thereof) arise out of or are based
upon an untrue statement or alleged untrue statement of a material fact
contained in any Preliminary Prospectus, the Registration Statement or the
Prospectus, or any amendment or supplement thereto, or arise out of or are based
upon the omission or alleged omission to state therein a material fact required
to be stated therein or necessary to make the statements therein not misleading,
in each case to the extent, but only to the extent, that such untrue statement
or alleged untrue statement or omission or alleged omission was made in any
Preliminary Prospectus, the Registration Statement or the Prospectus or any such
amendment or supplement in reliance upon and in conformity with written
information furnished to the Company by such Underwriter through 
expressly for use therein; and will reimburse the Company for any legal or
other expenses reasonably incurred by the Company in connection with
investigating or defending any such action or claim as such expenses are
incurred.

         (c) Promptly after receipt by an indemnified party under subsection (a)
or (b) above of notice of the commencement of any action, such indemnified party
shall, if a claim in respect thereof is to be made against the indemnifying
party under such subsection, notify the


                                      -17-

<PAGE>


indemnifying party in writing of the commencement thereof; but the omission so
to notify the indemnifying party shall not relieve it from any liability which
it may have to any indemnified party otherwise than under such subsection. In
case any such action shall be brought against any indemnified party and it shall
notify the indemnifying party of the commencement thereof, the indemnifying
party shall be entitled to participate therein and, to the extent that it shall
wish, jointly with any other indemnifying party similarly notified, to assume
the defense thereof, with counsel satisfactory to such indemnified party (who
shall not, except with the consent of the indemnified party, be counsel to the
indemnifying party), and, after notice from the indemnifying party to such
indemnified party of its election so to assume the defense thereof, the
indemnifying party shall not be liable to such indemnified party under such
subsection for any legal expenses of other counsel or any other expenses, in
each case subsequently incurred by such indemnified party, in connection with
the defense thereof other than reasonable costs of investigation. No
indemnifying party shall, without the written consent of the indemnified party,
effect the settlement or compromise of, or consent to the entry of any judgment
with respect to, any pending or threatened action or claim in respect of which
indemnification or contribution may be sought hereunder (whether or not the
indemnified party is an actual or potential party to such action or claim)
unless such settlement, compromise or judgment (i) includes an unconditional
release of the indemnified party from all liability arising out of such action
or claim and (ii) does not include a statement as to or an admission of fault,
culpability or a failure to act, by or on behalf of any indemnified party.

         (d) If the indemnification provided for in this Section 8 is
unavailable to or insufficient to hold harmless an indemnified party under
subsection (a) or (b) above in respect of any losses, claims, damages or
liabilities (or actions in respect thereof) referred to therein, then each
indemnifying party shall contribute to the amount paid or payable by such
indemnified party as a result of such losses, claims, damages or liabilities (or
actions in respect thereof) in such proportion as is appropriate to reflect the
relative benefits received by the Company on the one hand and the Underwriters
on the other from the offering of the Shares. If, however, the allocation
provided by the immediately preceding sentence is not permitted by applicable
law or if the indemnified party failed to give the notice required under
subsection (c) above, then each indemnifying party shall contribute to such
amount paid or payable by such indemnified party in such proportion as is
appropriate to reflect not only such relative benefits but also the relative
fault of the Company on the one hand and the Underwriters on the other in
connection with the statements or omissions which resulted in such losses,
claims, damages or liabilities (or actions in respect thereof), as well as any
other relevant equitable considerations. The relative benefits received by the
Company on the one hand and the Underwriters on the other shall be deemed to be
in the same proportion as the total net proceeds from the offering (before
deducting expenses) received by the Company bear to the total underwriting
discounts and commissions received by the Underwriters, in each case as set
forth in the table on the cover page of the Prospectus. The relative fault shall
be determined by reference to, among other things, whether the untrue or alleged
untrue statement of a material fact or the omission or alleged omission to state
a material fact relates to information supplied by the Company on the one hand
or the Underwriters on the other and the parties' relative intent, knowledge,
access to information and opportunity to correct or prevent such statement or
omission. The Company and the Underwriters agree that it would not be just and
equitable if contributions pursuant to this subsection (e) were determined by
PRO RATA allocation (even if the Underwriters were treated as one entity for
such purpose) or by any other method of allocation which does not take account
of the equitable considerations referred to above in this subsection (e). The
amount paid or payable by an indemnified party as a result of the losses,
claims, damages or liabilities (or actions in respect thereof) referred to above
in this subsection (e) shall be deemed to include any legal or other expenses
reasonably incurred by such indemnified party in


                                      -18-

<PAGE>


connection with investigating or defending any such action or claim.
Notwithstanding the provisions of this subsection (e), no Underwriter shall be
required to contribute any amount in excess of the amount by which the total
price at which the Shares underwritten by it and distributed to the public were
offered to the public exceeds the amount of any damages which such Underwriter
has otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission. No person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Act) shall be
entitled to contribution from any person who was not guilty of such fraudulent
misrepresentation. The Underwriters' obligations in this subsection (e) to
contribute are several in proportion to their respective underwriting
obligations and not joint.

         (e) The obligations of the Company under this Section 8 shall be in
addition to any liability which the Company may otherwise have and shall extend,
upon the same terms and conditions, to each person, if any, who controls any
Underwriter within the meaning of the Act; and the obligations of the
Underwriters under this Section 8 shall be in addition to any liability which
the respective Underwriters may otherwise have and shall extend, upon the same
terms and conditions, to each officer and director of the Company (including any
person who, with his or her consent, is named in the Registration Statement as
about to become a director of the Company) and to each person, if any, who
controls the Company within the meaning of the Act.

9. (a) If any Underwriter shall default in its obligation to purchase the Shares
which it has agreed to purchase hereunder at a Time of Delivery, you may in your
discretion arrange for you or another party or other parties to purchase such
Shares on the terms contained herein. If within thirty-six hours after such
default by any Underwriter you do not arrange for the purchase of such Shares,
then the Company shall be entitled to a further period of thirty-six hours
within which to procure another party or other parties satisfactory to you to
purchase such Shares on such terms. In the event that, within the respective
prescribed periods, you notify the Company that you have so arranged for the
purchase of such Shares, or the Company notify you that they have so arranged
for the purchase of such Shares, you or the Company shall have the right to
postpone such Time of Delivery for a period of not more than seven days, in
order to effect whatever changes may thereby be made necessary in the
Registration Statement or the Prospectus, or in any other documents or
arrangements, and the Company agrees to file promptly any amendments to the
Registration Statement or the Prospectus which in your opinion may thereby be
made necessary. The term "Underwriter" as used in this Agreement shall include
any person substituted under this Section with like effect as if such person had
originally been a party to this Agreement with respect to such Shares.

         (b) If, after giving effect to any arrangements for the purchase of the
Shares of a defaulting Underwriter or Underwriters by you and the Company as
provided in subsection (a) above, the aggregate number of such Shares which
remains unpurchased does not exceed one-eleventh of the aggregate number of all
the Shares to be purchased at such Time of Delivery, then the Company shall have
the right to require each non-defaulting Underwriter to purchase the number of
shares which such Underwriter agreed to purchase hereunder at such Time of
Delivery and, in addition, to require each non-defaulting Underwriter to
purchase its pro rata share (based on the number of Shares which such
Underwriter agreed to purchase hereunder) of the Shares of such defaulting
Underwriter or Underwriters for which such arrangements have not been made; but
nothing herein shall relieve a defaulting Underwriter from liability for its
default.

         (c) If, after giving effect to any arrangements for the purchase of the
Shares of a defaulting Underwriter or Underwriters by you and the Company as
provided in subsection (a)


                                      -19-

<PAGE>


above, the aggregate number of such Shares which remains unpurchased exceeds
one-eleventh of the aggregate number of all the Shares to be purchased at such
Time of Delivery, or if the Company shall not exercise the right described in
subsection (b) above to require non-defaulting Underwriters to purchase Shares
of a defaulting Underwriter or Underwriters, then this Agreement (or, with
respect to the Second Time of Delivery, the obligations of the Underwriters to
purchase and of the Company to sell the Optional Shares) shall thereupon
terminate, without liability on the part of any non-defaulting Underwriter or
the Company, except for the expenses to be borne by the Company and the
Underwriters as provided in Section 6 hereof and the indemnity and contribution
agreements in Section 8 hereof; but nothing herein shall relieve a defaulting
Underwriter from liability for its default.

10. The respective indemnities, agreements, representations, warranties and
other statements of the Company and the several Underwriters, as set forth in
this Agreement or made by or on behalf of them, respectively, pursuant to this
Agreement, shall remain in full force and effect, regardless of any
investigation (or any statement as to the results thereof) made by or on behalf
of any Underwriter or any controlling person of any Underwriter, or the Company,
or any officer or director or controlling person of the Company, and shall
survive delivery of and payment for the Shares.

11. If this Agreement shall be terminated pursuant to Section 9 hereof, the
Company shall be under no liability to any Underwriter except as provided in
Sections 6 and 8 hereof; but, if for any other reason, any Shares are not
delivered by or on behalf of the Company as provided herein, the Company will
reimburse the Underwriters through you for all out-of-pocket expenses approved
in writing by you, including fees and disbursements of counsel, in each case
reasonably incurred by the Underwriters in making preparations for the purchase,
sale and delivery of the Shares not so delivered, but the Company shall then be
under no further liability to any Underwriter with respect to Shares not so
delivered except as provided in Sections 6 and 8 hereof.

12. In all dealings hereunder, you shall act on behalf of each of the
Underwriters, and the parties hereto shall be entitled to act and rely upon any
statement, request, notice or agreement on behalf of any Underwriter made or
given by you jointly or by               on behalf of you as the
representatives.

        All statements, requests, notices and agreements hereunder shall be in
writing, and if to the Underwriters shall be delivered or sent by mail, telex or
facsimile transmission to you as the representatives in care of               
                  ; and if to the Company shall be delivered or sent by
mail to the address of the Company set forth in the Registration Statement,
Attention: Secretary; provided, however, that any notice to an Underwriter
pursuant to Section 8(c) hereof shall be delivered or sent by mail, telex or
facsimile transmission to such Underwriter at its address set forth in its
Underwriters' Questionnaire, or telex constituting such Questionnaire, which
address will be supplied to the Company. Any such statements, requests, notices
or agreements shall take effect upon receipt thereof.

13. This Agreement shall be binding upon, and inure solely to the benefit of,
the Underwriters, the Company and, to the extent provided in Sections 8 and 10
hereof, the officers and directors of the Company and each person who controls
the Company or any Underwriter, and their respective heirs, executors,
administrators, successors and assigns, and no other person shall acquire or
have any right under or by virtue of this Agreement. No purchaser of


                                      -20-

<PAGE>


any of the Shares from any Underwriter shall be deemed a successor or assign by
reason merely of such purchase.

14. Time shall be of the essence of this Agreement. As used herein, the term
"business day" shall mean any day when the Commission's office in Washington,
D.C. is open for business.

15. This Agreement shall be governed by and construed in accordance with the
laws of the State of New York.

16. This Agreement may be executed by any one or more of the parties hereto in
any number of counterparts, each of which shall be deemed to be an original, but
all such counterparts shall together constitute one and the same instrument.



                                      -21-

<PAGE>


         If the foregoing is in accordance with your understanding, please sign
and return to us one for the Company and each of the Representatives plus one
for each counsel and the Custodian counterparts hereof, and upon the acceptance
hereof by you, on behalf of each of the Underwriters, this letter and such
acceptance hereof shall constitute a binding agreement between each of the
Underwriters and the Company. It is understood that your acceptance of this
letter on behalf of each of the Underwriters is pursuant to the authority set
forth in a form of Agreement among Underwriters, the form of which shall be
submitted to the Company for examination upon request, but without warranty on
your part as to the authority of the signers thereof.

                                             Very truly yours,

                                             Sonus Networks, Inc.

                                             By: 
                                                 ----------------------------
                                                 Name:
                                                 Title:



Accepted as of the date hereof:


[Co-Representatives]



By:
    -------------------------------------


    On behalf of each of the Underwriters



                                      -22-

<PAGE>


                                   SCHEDULE I


<TABLE>
<CAPTION>

                                                                                NUMBER OF OPTIONAL
                                                                                SHARES TO BE
                                                         TOTAL NUMBER OF        PURCHASED IF
                                                         FIRM SHARES            MAXIMUM OPTION
UNDERWRITER                                              TO BE PURCHASED        EXERCISED
-----------                                              ---------------        -----------------
<S>                                                      <C>                    <C>
                    ..................................
                    ..................................
                    ..................................
                    ..................................
____________________..................................
____________________..................................
____________________..................................
____________________..................................
____________________..................................
____________________..................................
____________________..................................   ______________         _____________

              Total...................................   ______________         _____________
                                                         ______________         _____________
</TABLE>





<PAGE>


                                  SCHEDULE III




                                       -2-

<PAGE>


                               LOCK-UP AGREEMENTS




                                       -3-

<PAGE>



                                     ANNEX I


         Pursuant to Section 7(e) of the Underwriting Agreement, the accountants
shall furnish letters to the Underwriters to the effect that:

               (i) They are independent certified public accountants with
         respect to the Company and its subsidiaries within the meaning of the
         Act and the applicable published rules and regulations thereunder;

               (ii) In their opinion, the financial statements and any
         supplementary financial information and schedules (and, if applicable,
         financial forecasts and/or pro forma financial information) examined by
         them and included or incorporated by reference in the Registration
         Statement or the Prospectus comply as to form in all material respects
         with the applicable accounting requirements of the Act or the Exchange
         Act, as applicable, and the related published rules and regulations
         thereunder; and, if applicable, they have made a review in accordance
         with standards established by the American Institute of Certified
         Public Accountants of the consolidated interim financial statements,
         selected financial data, pro forma financial information, financial
         forecasts and/or condensed financial statements derived from audited
         financial statements of the Company for the periods specified in such
         letter, as indicated in their reports thereon, copies of which have
         been furnished to the representatives of the Underwriters (the
         "Representatives") and are attached hereto;

               (iii) They have made a review in accordance with standards
         established by the American Institute of Certified Public Accountants
         of the unaudited condensed consolidated statements of income,
         consolidated balance sheets and consolidated statements of cash flows
         included in the Prospectus and/or included in the Company's quarterly
         report on Form 10-Q incorporated by reference into the Prospectus as
         indicated in their reports thereon copies of which are attached hereto;
         and on the basis of specified procedures including inquiries of
         officials of the Company who have responsibility for financial and
         accounting matters regarding whether the unaudited condensed
         consolidated financial statements referred to in paragraph (vi)(A)(i)
         below comply as to form in all material respects with the applicable
         accounting requirements of the Act and the Exchange Act and the related
         published rules and regulations, nothing came to their attention that
         caused them to believe that the unaudited condensed consolidated
         financial statements do not comply as to form in all material respects
         with the applicable accounting requirements of the Act and the Exchange
         Act and the related published rules and regulations;

               (iv) The unaudited selected financial information with respect to
         the consolidated results of operations and financial position of the
         Company for the five most recent fiscal years included in the
         Prospectus and included or incorporated by reference in Item 6 of the
         Company's Annual Report on Form 10-K for the most recent fiscal year
         agrees with the corresponding amounts (after restatement where
         applicable) in the audited consolidated financial statements for such
         five fiscal years which were included or incorporated by reference in
         the Company's Annual Reports on Form 10-K for such fiscal years;

               (v) They have compared the information in the Prospectus under
         selected captions with the disclosure requirements of Regulation S-K
         and on the basis of limited procedures specified in such letter nothing
         came to their attention as a result of the foregoing procedures that
         caused them to believe that this information does not conform


                                       -4-

<PAGE>


         in all material respects with the disclosure requirements of Items 301,
         302, 402 and 503(d), respectively, of Regulation S-K;

               (vi) On the basis of limited procedures, not constituting an
         examination in accordance with generally accepted auditing standards,
         consisting of a reading of the unaudited financial statements and other
         information referred to below, a reading of the latest available
         interim financial statements of the Company and its subsidiaries,
         inspection of the minute books of the Company and its subsidiaries
         since the date of the latest audited financial statements included or
         incorporated by reference in the Prospectus, inquiries of officials of
         the Company and its subsidiaries responsible for financial and
         accounting matters and such other inquiries and procedures as may be
         specified in such letter, nothing came to their attention that caused
         them to believe that:

                      (A) (i) the unaudited condensed consolidated statements of
               income, consolidated balance sheets and consolidated statements
               of cash flows included in the Prospectus and/or included or
               incorporated by reference in the Company's Quarterly Reports on
               Form 10-Q incorporated by reference in the Prospectus do not
               comply as to form in all material respects with the applicable
               accounting requirements of the Exchange Act as it applies to Form
               10-Q and the related published rules and regulations, or (ii) any
               material modifications should be made to the unaudited condensed
               consolidated statements of income, consolidated balance sheets
               and consolidated statements of cash flows included in the
               Prospectus or included in the Company's Quarterly Reports on Form
               10-Q incorporated by reference in the Prospectus, for them to be
               conformity with generally accepted accounting principles;

                      (B) any other unaudited income statement data and balance
               sheet items included in the Prospectus do not agree with the
               corresponding items in the unaudited consolidated financial
               statements from which such data and items were derived, and any
               such unaudited data and items were not determined on a basis
               substantially consistent with the basis for the corresponding
               amounts in the audited consolidated financial statements included
               or incorporated by reference in the Company's Annual Report on
               Form 10-K for the most recent fiscal year;

                      (C) the unaudited financial statements which were not
               included in the Prospectus but from which were derived the
               unaudited condensed financial statements referred to in clause
               (A) and any unaudited income statement data and balance sheet
               items included in the Prospectus and referred to in clause (B)
               were not determined on a basis substantially consistent with the
               basis for the audited financial statements included or
               incorporated by reference in the Company's Annual Report on Form
               10-K for the most recent fiscal year;

                      (D) any unaudited pro forma consolidated condensed
               financial statements included or incorporated by reference in the
               Prospectus do not comply as to form in all material respects with
               the applicable accounting requirements of the Act and the
               published rules and regulations thereunder or the pro forma
               adjustments have not been properly applied to the historical
               amounts in the compilation of those statements;

                      (E) as of a specified date not more than five days prior
               to the date of such letter, there have been any changes in the
               consolidated capital stock (other than issuances of capital stock
               upon exercise of options and stock appreciation rights, upon
               earn-outs of performance shares and upon conversions of
               convertible securities, in each case which were outstanding on
               the date of the latest balance


                                       -5-

<PAGE>


               sheet included or incorporated by reference in the Prospectus)
               or any increase in the consolidated long-term debt of the
               Company and its subsidiaries, or any decreases in consolidated
               net current assets or stockholders' equity or other items
               specified by the Representatives, or any increases in any
               items specified by the Representatives, in each case as
               compared with amounts shown in the latest balance sheet
               included or incorporated by reference in the Prospectus,
               except in each case for changes, increases or decreases which
               the Prospectus discloses have occurred or may occur or which
               are described in such letter; and

                      (F) for the period from the date of the latest financial
               statements included or incorporated by reference in the
               Prospectus to the specified date referred to in clause (E) there
               were any decreases in consolidated net revenues or operating
               profit or the total or per share amounts of consolidated net
               income or other items specified by the Representatives, or any
               increases in any items specified by the Representatives, in each
               case as compared with the comparable period of the preceding year
               and with any other period of corresponding length specified by
               the Representatives, except in each case for increases or
               decreases which the Prospectus discloses have occurred or may
               occur or which are described in such letter; and

               (vii) In addition to the examination referred to in their
         report(s) included or incorporated by reference in the Prospectus and
         the limited procedures, inspection of minute books, inquiries and other
         procedures referred to in paragraphs (iii) and (vi) above, they have
         carried out certain specified procedures, not constituting an
         examination in accordance with generally accepted auditing standards,
         with respect to certain amounts, percentages and financial information
         specified by the Representatives which are derived from the general
         accounting records of the Company and its subsidiaries, which appear in
         the Prospectus (excluding documents incorporated by reference) or in
         Part II of, or in exhibits and schedules to, the Registration Statement
         specified by the Representatives or in documents incorporated by
         reference in the Prospectus specified by the Representatives, and have
         compared certain of such amounts, percentages and financial information
         with the accounting records of the Company and its subsidiaries and
         have found them to be in agreement.


                                       -6-

<PAGE>


                                   ANNEX I(a)




                                      -7-

<PAGE>


                                   ANNEX I(b)




                                      -8-

<PAGE>


                                   ANNEX II(a)




                                      -9-

<PAGE>


                                   ANNEX II(b)




                                      -10-

<PAGE>


                                   ANNEX II(c)




                                      -11-

<PAGE>



                                   ANNEX II(d)




                                      -12-

<PAGE>


                                   ANNEX II(e)




                                      -13-

<PAGE>


                                                                       EXHIBIT A


                            FORM OF LOCK-UP AGREEMENT




                                      -14-





<PAGE>


                                                                     Exhibit 1.2


                              SONUS NETWORKS, INC.


                                  ------------


                      FORM OF UNDERWRITING AGREEMENT (DEBT)


                                                           ---------------, ----




Ladies and Gentlemen:


         Sonus Networks, Inc., a Delaware corporation (the "COMPANY"), proposes,
subject to the terms and conditions stated herein, to issue and sell to the
Underwriters named in Schedule I hereto (the "UNDERWRITERS") an aggregate of
$[___________] principal amount of _____________ (the "FIRM SECURITIES") and, at
the election of the Underwriters, up to an aggregate of $[___________]
additional aggregate principal amount (the "OPTIONAL SECURITIES") (the Firm
Securities and the Optional Securities which the Underwriters may elect to
purchase pursuant to Section 2 hereof are herein collectively called the
"SECURITIES").

         1. The Company represents and warrants to, and agrees with, each of the
Underwriters that:

                (a) A registration statement on Form S-3 (File No. 333-....)
         (the "INITIAL REGISTRATION STATEMENT") in respect of the Securities has
         been filed with the Securities and Exchange Commission (the
         "COMMISSION"); the Initial Registration Statement and any
         post-effective amendment thereto, each in the form heretofore delivered
         to you, and, excluding exhibits thereto but including all documents
         incorporated by reference in the prospectus contained therein, to you
         for each of the other Underwriters,
 have been declared effective by the
         Commission in such form; other than a registration statement, if any,
         increasing the size of the offering (a "RULE 462(b) REGISTRATION
         STATEMENT"), filed pursuant to Rule 462(b) under the Securities Act of
         1933, as amended (the "ACT"), which became effective upon filing, no
         other document with respect to the Initial Registration Statement or
         document incorporated by reference therein has heretofore been filed
         with the Commission; and no stop order suspending the effectiveness of
         the Initial Registration Statement, any post-effective amendment
         thereto or the Rule 462(b) Registration Statement, if any, has been
         issued and no proceeding for that purpose has been initiated or
         threatened by the Commission (the form of



<PAGE>


         prospectus to be used in connection with the issuance and sale of the
         Securities included in the Initial Registration Statement is
         hereinafter called the "BASIC PROSPECTUS"; the form of prospectus
         supplement included in the Initial Registration Statement is hereby
         called the "PROSPECTUS SUPPLEMENT"; the Basic Prospectus, as
         supplemented by the Prospectus Supplement, in the form in which it
         shall be filed with the Commission pursuant to Rule 424(b) under the
         Act, is hereinafter called the "PROSPECTUS"; any preliminary prospectus
         included in the Initial Registration Statement or filed with the
         Commission pursuant to Rule 424(a) of the rules and regulations of the
         Commission under the Act is hereinafter called a "PRELIMINARY
         PROSPECTUS"; the various parts of the Initial Registration Statement
         and the Rule 462(b) Registration Statement, if any, including all
         exhibits thereto and including (i) the information contained in the
         Prospectus filed with the Commission pursuant to Rule 424(b) under the
         Act in accordance with Section 5(a) hereof and deemed by virtue of Rule
         430A under the Act to be part of the Initial Registration Statement at
         the time it was declared effective and (ii) the documents incorporated
         by reference in the Prospectus contained in the Initial Registration
         Statement at the time such part of the Initial Registration Statement
         became effective, each as amended at the time such part of the Initial
         Registration Statement became effective or such part of the Rule 462(b)
         Registration Statement, if any, became or hereafter becomes effective,
         are hereinafter collectively called the "REGISTRATION STATEMENT"; any
         reference herein to the Registration Statement, Basic Prospectus,
         Prospectus Supplement, Preliminary Prospectus or Prospectus shall be
         deemed to refer to and include the documents incorporated by reference
         therein pursuant to Item 12 of Form S-3 under the Act, as of the date
         of such Registration Statement, Basic Prospectus, Prospectus
         Supplement, Preliminary Prospectus or Prospectus, as the case may be;
         any reference to any amendment or supplement to the Registration
         Statement, Basic Prospectus, Prospectus Supplement, Preliminary
         Prospectus or Prospectus shall be deemed to refer to and include any
         documents filed after the date of such Registration Statement, Basic
         Prospectus, Prospectus Supplement, Preliminary Prospectus or
         Prospectus, as the case may be, under the Securities Exchange Act of
         1934, as amended (the "EXCHANGE ACT"), and incorporated by reference in
         such Registration Statement, Basic Prospectus, Prospectus Supplement,
         Preliminary Prospectus or Prospectus, as the case may be; and any
         reference to any amendment to the Registration Statement shall be
         deemed to refer to and include any annual report of the Company filed
         pursuant to Section 13(a) or 15(d) of the Exchange Act after the
         effective date of the Initial Registration Statement that is
         incorporated by reference in the Registration Statement);

                (b) No order preventing or suspending the use of any Preliminary
         Prospectus has been issued by the Commission, and each Preliminary
         Prospectus, at the time of filing thereof, conformed in all material
         respects to the requirements of the Act and the Trust Indenture Act of
         1939, as amended (the "TRUST INDENTURE ACT"), and the rules and
         regulations of the Commission thereunder, and did not contain an untrue
         statement of a material fact or omit to state a material fact required
         to be stated therein or necessary to make the statements therein, in
         the light of the circumstances under which they were made, not
         misleading; PROVIDED, HOWEVER, that this representation and warranty
         shall not apply to any statements or omissions made in reliance upon
         and in conformity with information furnished in writing to the Company
         by an Underwriter through                   expressly for use
         therein;

                (c) The documents incorporated by reference in the Prospectus,
         when they became effective or were filed with the Commission, as the
         case may be, conformed in all material respects to the requirements of
         the Act or the Exchange Act, as applicable, and the rules and


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         regulations of the Commission thereunder, and none of such documents
         contained an untrue statement of a material fact or omitted to state a
         material fact required to be stated therein or necessary to make the
         statements therein not misleading; and any further documents so filed
         and incorporated by reference in the Prospectus or any further
         amendment or supplement thereto, when such documents become effective
         or are filed with the Commission, as the case may be, will conform in
         all material respects to the requirements of the Act or the Exchange
         Act, as applicable, and the rules and regulations of the Commission
         thereunder and will not contain an untrue statement of a material fact
         or omit to state a material fact required to be stated therein or
         necessary to make the statements therein not misleading; PROVIDED,
         HOWEVER, that this representation and warranty shall not apply to any
         statements or omissions made in reliance upon and in conformity with
         information furnished in writing to the Company by an Underwriter
         through                        expressly for use therein;

                (d) The Registration Statement conforms, and the Prospectus and
         any further amendments or supplements to the Registration Statement or
         the Prospectus will conform, in all material respects to the
         requirements of the Act and the Trust Indenture Act and the rules and
         regulations of the Commission thereunder and do not and will not, as of
         the applicable effective date as to the Registration Statement and any
         amendment thereto and as of the applicable filing date as to the
         Prospectus and any amendment or supplement thereto, contain an untrue
         statement of a material fact or omit to state a material fact required
         to be stated therein or necessary to make the statements therein not
         misleading; PROVIDED, HOWEVER, that this representation and warranty
         shall not apply to any statements or omissions made in reliance upon
         and in conformity with information furnished in writing to the Company
         by an Underwriter through                          expressly for use
         therein;

                (e) There are no contracts or other documents required to be
         described in the Registration Statement or to be filed as exhibits to
         the Registration Statement by the Act or by the rules and regulations
         thereunder which have not been described or filed as required; the
         contracts so described in the Prospectus to which the Company or any of
         its subsidiaries is a party have been duly authorized, executed and
         delivered by the Company and its subsidiaries, as are party thereto,
         constitute valid and binding agreements of the Company and its
         subsidiaries, as are party thereto, are enforceable against the Company
         and its subsidiaries, as are party thereto, in accordance with their
         respective terms and are in full force and effect on the date hereof;
         to the best of the Company's knowledge, the contracts so described in
         the Prospectus to which the Company or any of its subsidiaries is a
         party are enforceable by the Company and its subsidiaries, as are party
         thereto, against the other parties thereto in accordance with their
         respective terms; and neither the Company nor any of its subsidiaries,
         nor, to the best of the Company's knowledge, any other party is in
         breach of or default under any of such contracts, except for such
         breaches or defaults that, singly or in the aggregate, would not result
         in a material adverse change in or affecting the business, assets,
         management, financial condition or results of operations of the Company
         and its subsidiaries taken as a whole;

                (f) Neither the Company nor any of its subsidiaries has
         sustained since the date of the latest audited financial statements
         included or incorporated by reference in the Prospectus any material
         loss or interference with its business from fire, explosion, flood or
         other calamity, whether or not covered by insurance, or from any labor
         dispute or court or governmental action, order or decree, otherwise
         than as set forth in the Prospectus; and, since the


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         respective dates as of which information is given in the Registration
         Statement and the Prospectus, there has not been any change in the
         capital stock (other than issuances of shares of common stock, $0.001
         par value per share (the "STOCK"), pursuant to Company stock option,
         stock incentive or stock purchase plans described in the Registration
         Statement and Prospectus or in connection with the acquisition of
         telecom technologies, inc. ("TTI"), as described in the Registration
         Statement and Prospectus) or long-term debt (other than as described in
         the Registration Statement and Prospectus) of the Company or any of its
         subsidiaries or any material adverse change, or any development
         involving a prospective material adverse change, in or affecting the
         business, assets, management, financial position, or results of
         operations of the Company and its subsidiaries, taken as a whole;

                (g) None of the Company and its subsidiaries owns any real
         property; each of the Company and its subsidiaries has good and
         marketable title to all personal property owned by it, free and clear
         of all liens, encumbrances and defects except such as are described in
         the Prospectus or such as do not materially affect the value of such
         property and do not interfere with the use made and proposed to be made
         of such property by the Company and its subsidiaries; and any real
         property and buildings held under lease by the Company or any of its
         subsidiaries are held under valid, subsisting and enforceable leases
         with such exceptions as are not material and do not interfere with the
         use made and proposed to be made of such property and buildings by the
         Company and its subsidiaries; the Company and its subsidiaries own or
         lease all such properties as are necessary to their operations as now
         conducted, except where the failure to so own or lease would not,
         singly or in the aggregate, result in a material adverse change in or
         affecting the business, assets, management, financial condition or
         results of operations of the Company and its subsidiaries taken as a
         whole;

                (h) Each of the Company and its subsidiaries has been duly
         incorporated and is validly existing as a corporation in good standing
         under the laws of its jurisdiction of organization, each with full
         power and authority (corporate and other) to own its properties and
         conduct its business as described in the Prospectus, and has been duly
         qualified as a foreign corporation for the transaction of business and
         is in good standing under the laws of each other jurisdiction in which
         it owns or leases properties or conducts any business so as to require
         such qualification, or is subject to no material liability or
         disability by reason of the failure to be so qualified in any such
         jurisdiction;

                (i) The Company has an authorized capitalization as set forth in
         the Prospectus, and all of the issued shares of capital stock of the
         Company have been duly authorized and validly issued and are fully paid
         and non-assessable; and all of the issued shares of capital stock of
         each subsidiary of the Company have been duly authorized and validly
         issued, are fully paid and non-assessable and (except for directors'
         qualifying shares) are owned directly or indirectly by the Company,
         free and clear of all liens, encumbrances, equities or claims except
         such as are described in the Prospectus; except as disclosed in or
         contemplated by the Prospectus and the consolidated financial
         statements of the Company, and the related notes thereto, included in
         the Prospectus, neither the Company nor any subsidiary has outstanding
         any options to purchase, or any preemptive rights or other rights to
         subscribe for or to purchase any securities or obligations convertible
         into, or any contracts or commitments to issue or sell, shares of its
         capital stock or any such options, rights, convertible securities or
         obligations; and the description of the Company's stock option and
         stock purchase plans and the options or other rights granted and
         exercised thereunder set forth in the Prospectus


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<PAGE>


         accurately and fairly presents the information required to be shown
         with respect to such plans, options and rights;

                (j) The Securities have been duly authorized and, when issued
         and delivered pursuant to this Agreement, will have been duly executed,
         authenticated, issued and delivered and will constitute valid and
         legally binding obligations of the Company entitled to the benefits
         provided by the indenture dated as of __________, _____ (the
         "INDENTURE") between the Company and The Bank of New York, as Trustee
         (the "TRUSTEE"), under which they are to be issued, which is
         substantially in the form filed as an exhibit to the Registration
         Statement; the Indenture has been duly authorized and duly qualified
         under the Trust Indenture Act and constitutes a valid and legally
         binding instrument, enforceable in accordance with its terms, subject,
         as to enforcement, to bankruptcy, insolvency, reorganization and other
         laws of general applicability relating to or affecting creditors'
         rights and to general equity principles; the Securities and the
         Indenture will conform to the descriptions thereof in the Prospectus;
         and no preemptive rights or other rights to subscribe for or purchase
         exist with respect to the issuance and sale of the Securities by the
         Company pursuant to this Agreement;

                (k) The Company has full corporate power and authority to enter
         into this Agreement; this Agreement has been duly authorized, executed
         and delivered by the Company, constitutes a valid and binding
         obligation of the Company and is enforceable against the Company in
         accordance with its terms;

                (l) The issue and sale of the Securities and the compliance by
         the Company with all of the provisions of the Securities, the Indenture
         and this Agreement and the consummation of the transactions herein and
         therein contemplated will not conflict with or result in a breach or
         violation of any of the terms or provisions of, or constitute a default
         under, any material indenture, mortgage, deed of trust, loan agreement
         or other agreement or instrument to which the Company or any of its
         subsidiaries is a party or by which the Company or any of its
         subsidiaries is bound or to which any of the property or assets of the
         Company or any of its subsidiaries is subject, nor will such action
         result in any violation of the provisions of the Certificate of
         Incorporation or By-laws of the Company or any statute or any order,
         rule or regulation of any court or governmental agency or body having
         jurisdiction over the Company or any of its subsidiaries or any of
         their properties; and no consent, approval, authorization, order,
         filing, registration or qualification of or with any such court or
         governmental agency or body is required for the issue and sale of the
         Securities or the consummation by the Company of the transactions
         contemplated by this Agreement or the Indenture, except the
         registration under the Act of the Securities, such as have been
         obtained under the Trust Indenture Act and such consents, approvals,
         authorizations, registrations or qualifications as may be required
         under state securities or Blue Sky laws in connection with the purchase
         and distribution of the Securities by the Underwriters;

                (m) Neither the Company nor any of its subsidiaries is in
         violation of its Certificate of Incorporation or By-laws or in default
         in the performance or observance of any obligation, covenant or
         condition contained in any indenture, mortgage, deed of trust, loan
         agreement, lease or other agreement or instrument to which it is a
         party or by which it or any of its properties may be bound except for
         such violations or defaults that would not, singly or in the aggregate,
         result in a material adverse change in or effect on the business,
         assets,


                                      -5-

<PAGE>


         management, financial position or results of operations of the Company
         and its subsidiaries taken as a whole;

                (n) The statements set forth in the Prospectus under the caption
         "Description of Notes", insofar as they purport to constitute a summary
         of the terms of the Securities, under the caption "Certain United
         States Federal Income Tax Considerations" and under the caption
         "Underwriting", insofar as they purport to describe the provisions of
         the laws and documents referred to therein, are accurate, complete and
         fair;

                (o) Other than as set forth in the Prospectus, there are no
         legal or governmental actions, suits or proceedings pending or, to the
         best of the Company's knowledge, threatened to which the Company or any
         of its subsidiaries is or may be a party or of which any property owned
         or leased by the Company or any of its subsidiaries is or may be the
         subject, which actions, suits or proceedings are required to be
         described in the Registration Statement by the Act or the rules and
         regulations thereunder or which might, singly or in the aggregate,
         prevent or adversely affect the transactions contemplated by this
         Agreement or result in a material adverse change in or affecting the
         business, assets, management, financial position (after giving effect
         to the offering of the Securities) or results of operations of the
         Company and its subsidiaries taken as a whole; and, to the best of the
         Company's knowledge, no such proceedings are threatened or contemplated
         by governmental authorities or others; no labor disturbance by the
         employees of the Company or any of its subsidiaries exists or, to the
         knowledge of the Company, is imminent which might be expected to affect
         adversely the business, assets, management, financial position or
         results of operations of the Company and its subsidiaries taken as a
         whole; and neither the Company nor any of its subsidiaries is a party
         or subject to the provisions of any injunction, judgment, decree or
         order of any court, regulatory body, administrative agency or other
         governmental body;

                (p) The Company is not and, after giving effect to the offering
         and sale of the Securities, will not be an "investment company" or an
         entity "controlled" by an "investment company", as such terms are
         defined in the Investment Company Act of 1940, as amended (the
         "INVESTMENT COMPANY ACT");

                (q) Neither the Company nor any of its affiliates does business
         with the government of Cuba or with any person or affiliate located in
         Cuba within the meaning of Section 517.075, Florida Statutes;

                (r) The Company and its subsidiaries possess all licenses,
         certificates, authorizations or permits issued by the appropriate
         governmental or regulatory agencies or authorities that are necessary
         to enable them to own, lease and operate their respective properties
         and to carry on their respective businesses as currently conducted and
         which are material to the Company and its subsidiaries, and neither the
         Company nor any of its subsidiaries has received any notice of
         proceedings relating to the revocation or modification of any such
         license, certificate, authorization or permit which, singly or in the
         aggregate, would be expected to materially and adversely affect the
         business, assets, management, financial position or results of
         operations of the Company and its subsidiaries taken as a whole;

                (s) The consolidated financial statements and schedules of the
         Company and of TTI, and the related notes thereto, included in the
         Registration Statement and the Prospectus


                                      -6-

<PAGE>


         present fairly in all material respects the financial position of the
         Company and TTI, respectively as of the respective dates of such
         financial statements and schedules, and the results of operations and
         cash flows of the Company and TTI, respectively for the respective
         periods covered thereby; such statements, schedules and related notes
         have been prepared in accordance with generally accepted accounting
         principles applied on a consistent basis as certified by the
         independent public accountants named in paragraph (t) below; no other
         financial statements or schedules are required to be included in the
         Registration Statement; and the selected financial data set forth in
         the Prospectus under the captions "Summary Financial Information,"
         "Capitalization" and "Selected Financial Data" fairly present the
         information set forth therein on the basis stated in the Registration
         Statement;

                (t) Arthur Andersen LLP, who have certified certain financial
         statements of the Company and its subsidiaries, are independent public
         accountants as required by the Act and the rules and regulations of the
         Commission thereunder;

                (u) The Company and its subsidiaries are in compliance with any
         and all applicable foreign, federal, state and local laws and
         regulations relating to the protection of human health and safety,
         including without limitation those relating to occupational safety and
         health, the environment or hazardous or toxic substances or wastes,
         pollutants or contaminants, including without limitation those relating
         to the storage, handling or transportation of hazardous or toxic
         materials (collectively, "ENVIRONMENTAL LAWS"), except where such
         noncompliance with Environmental Laws would not, singly or in the
         aggregate, be expected to have a material adverse effect on the
         business, assets, management, financial position or results of
         operations of the Company and its subsidiaries taken as a whole. The
         Company, in its reasonable judgment, has concluded that, based upon
         facts and circumstances existing as of the date hereof, any costs or
         liabilities associated with Environmental Laws (including, without
         limitation, any capital or operating expenditures required for
         clean-up, closure of properties or compliance with Environmental Laws
         or any permit, license or approval, any related constraints on
         operating activities and any potential liabilities to third parties)
         would not, singly or in the aggregate, reasonably be expected to have a
         material adverse effect on the business, assets, management, financial
         position or results of operation of the Company and its subsidiaries
         taken as a whole;

                (v) Except as disclosed in the Prospectus, the Company and its
         subsidiaries own or have the right to use all trademarks, trade names,
         patent rights, copyrights, licenses, trade secrets, know-how,
         intellectual property and other similar rights necessary to conduct
         their business as now conducted; the Company has no knowledge of any
         infringement by the Company or any of its subsidiaries of any
         trademark, trade name, patent, copyright, license, trade secret,
         know-how, intellectual property or other similar rights of others; and
         there are no claims of infringement being made against the Company or
         any of its subsidiaries regarding trademark, trade name, patent,
         copyright, license, trade secret, know-how, intellectual property or
         other similar rights which could, singly or in the aggregate, have a
         material adverse effect on the business, assets, management, financial
         position or results of operations of the Company and its subsidiaries
         taken as a whole; the Company has no knowledge of any infringement by
         any third party of the trademark, trade name, patent, copyright,
         license, trade secret, know-how, intellectual property or other similar
         rights of the Company or any of its subsidiaries; none of the
         technology employed by the Company or any of its subsidiaries has been
         obtained or is being used by the Company or any of its


                                      -7-

<PAGE>


         subsidiaries in violation of any contractual or fiduciary obligation
         binding on the Company, its subsidiaries or any of their respective
         directors or executive officers or, to the best of the Company's
         knowledge, any of their respective employees or consultants or
         otherwise in violation of the rights of any person; none of the
         Company, its subsidiaries and, to the best of the Company's knowledge,
         any of its employees has received any written or, to the Company's
         knowledge, oral communications alleging that the Company or any of its
         subsidiaries has violated or, by conducting its business as proposed,
         would violate any of the intellectual property or proprietary rights of
         any other person except for such violations as would not, singly or in
         the aggregate, have a material adverse effect on the business, assets,
         management, financial position or results of operations of the Company
         and its subsidiaries taken as a whole; neither the execution nor
         delivery of this Agreement, nor the operation of the business of the
         Company and its subsidiaries by the employees of the Company or its
         subsidiaries, nor the conduct of the business of the Company and its
         subsidiaries as proposed, will, to the Company's knowledge, result in a
         breach or violation of the terms, conditions or provisions of, or
         constitute a default under, any contract, covenant or instrument under
         which any of such employees is now obligated except for such breaches,
         violations or defaults as would not, singly or in the aggregate, have a
         material adverse effect on the business, assets, management, financial
         position or results of operations of the Company and its subsidiaries
         taken as a whole; and the Company and its subsidiaries have taken and
         will maintain reasonable measures to prevent the unauthorized
         dissemination or publication of its confidential information or the
         confidential information of third parties in its possession;

                (w) The Company and each of its subsidiaries have filed all
         necessary federal, state, local and foreign income and franchise tax
         returns and have paid all taxes shown as due thereon; and the Company
         has no knowledge of any tax deficiencies which have been or might be
         asserted or threatened against the Company or any of its subsidiaries
         which could, singly or in the aggregate, materially and adversely
         affect the business, assets, management, financial position or results
         of operations of the Company and its subsidiaries taken as a whole;

                (x) Each of the Company and its subsidiaries maintains insurance
         of the types and in the amounts which it reasonably deems adequate for
         its business, including, but not limited to, insurance covering real
         and personal property owned or leased by the Company and its
         subsidiaries against theft, damage, destruction, acts of vandalism and
         all other risks customarily insured against, all of which insurance is
         in full force and effect;

                (y) Neither the Company nor any of its subsidiaries has at any
         time during the last five years (i) made any unlawful contribution to
         any candidate for foreign office, or failed to disclose fully any
         contribution in violation of law, or (ii) made any payment to any
         foreign, federal or state governmental officer or official, or other
         person charged with similar public or quasi-public duties, other than
         payments required or permitted by the laws of the United States or any
         jurisdiction thereof;

                (z) The Company has not taken and will not take, directly or
         indirectly through any of its directors, officers or controlling
         persons, any action which is designed to or which has constituted or
         which might reasonably be expected to cause or result in stabilization
         or manipulation of the price of any security of the Company to
         facilitate the sale or resale of the Shares; and


                                      -8-

<PAGE>


                (aa) The Company has filed all reports it has been required to
         file under the Securities Exchange Act of 1934, as amended (the
         "EXCHANGE ACT"); such reports when filed conformed in all material
         respects to the requirements of the Exchange Act and none of such
         reports contained an untrue statement of a material fact or omitted to
         state a material fact required to be stated therein or necessary to
         make the statements therein, in light of the circumstances under which
         they were made, not misleading.

         2. Subject to the terms and conditions herein set forth, (a) the
Company agrees to issue and sell to each of the Underwriters, and each of the
Underwriters agrees, severally and not jointly, to purchase from the Company, at
a purchase price of ___% of the principal amount thereof, plus accrued interest
from ________, ____ to the First Time of Delivery hereunder, the principal
amount of Securities set forth opposite the name of such Underwriter in Schedule
I hereto, and (b) in the event and to the extent that the Underwriters shall
exercise the election to purchase Optional Securities as provided below, the
Company agrees to issue and sell to each of the Underwriters, and each of the
Underwriters agrees, severally and not jointly, to purchase from the Company, at
the same purchase price set forth in clause (a) of this Section 2, that portion
of the aggregate principal amount of the Optional Securities as to which such
election shall have been exercised (to be adjusted by you so as to eliminate
fractions of less than $1,000.00 principal amount), determined by multiplying
such aggregate principal amount of Optional Securities by a fraction, the
numerator of which is the maximum aggregate principal amount of Optional
Securities which such Underwriter is entitled to purchase as set forth opposite
the name of such Underwriter in Schedule I hereto and the denominator of which
is the maximum aggregate principal amount of Optional Securities which all of
the Underwriters are entitled to purchase hereunder.

         The Company hereby grants to the Underwriters the right to purchase at
their election up to $_____ aggregate principal amount of Optional Securities,
at the purchase price set forth in clause (a) of the first paragraph of this
Section 2, for the sole purpose of covering sales of securities in excess of the
aggregate principal amount of Firm Securities. Any such election to purchase
Optional Securities may be exercised by written notice from you to the Company,
given within a period of 30 calendar days after the date of this Agreement,
setting forth the aggregate principal amount of Optional Securities to be
purchased and the date on which such Optional Securities are to be delivered, as
determined by you but in no event earlier than the First Time of Delivery (as
defined in Section 4 hereof) or, unless you and the Company otherwise agree in
writing, earlier than two or later than ten business days after the date of such
notice.

         3. Upon the authorization by you of the release of the Firm Securities,
the several Underwriters propose to offer the Firm Securities for sale upon the
terms and conditions set forth in the Prospectus.

         4. (a) The Securities to be purchased by each Underwriter hereunder
will be represented by one or more definitive global Securities in book-entry
form which will be deposited by or on behalf of the Company with The Depository
Trust Company ("DTC") or its designated custodian. The Company will deliver the
Securities to                , for the account of each Underwriter, against
payment by or on behalf of such Underwriter of the purchase price therefor by
wire transfer of Federal (same-day) funds to the account specified by the
Company to                        at least forty-eight hours in advance, by
causing DTC to credit the Securities to the account of                      at
DTC. The Company will cause the global Securities to be made available to
                      for checking at least twenty-four hours prior to the Time
of Delivery (as


                                      -9-

<PAGE>


defined below) at the office of DTC or its designated custodian (the "DESIGNATED
OFFICE"). The time and date of such delivery and payment shall be, with respect
to the Firm Securities, 9:30 a.m., New York City time, on ________, _____ or
such other time and date as                   and the Company may agree upon
in writing, and, with respect to the Optional Securities, 9:30 a.m., New York
City time, on the date specified by                    in the written notice
given by                      of the Underwriters' election to purchase such
Optional Securities, or such other time and date as                    and the
Company may agree upon in writing. Such time and date for delivery of the Firm
Securities is herein called the "FIRST TIME OF DELIVERY", such time and date for
delivery of the Optional Securities, if not the First Time of Delivery, is
herein called the "SECOND TIME OF DELIVERY", and each such time and date for
delivery is herein called a "TIME OF DELIVERY".

         (b) The documents to be delivered at each Time of Delivery by or on
behalf of the parties hereto pursuant to Section 7 hereof, including the
cross-receipt for the Securities and any additional documents requested by the
Underwriters pursuant to Section 7 hereof, will be delivered at the offices of
Bingham Dana LLP, Boston, Massachusetts 02110 (the "CLOSING LOCATION"), and the
Securities will be delivered at the Designated Office, all at such Time of
Delivery. A meeting will be held at the Closing Location at 6:00 p.m., New York
City time, on the New York Business Day next preceding such Time of Delivery, at
which meeting the final drafts of the documents to be delivered pursuant to the
preceding sentence will be available for review by the parties hereto. For the
purposes of this Section 4, "NEW YORK BUSINESS DAY" shall mean each Monday,
Tuesday, Wednesday, Thursday and Friday which is not a day on which banking
institutions in New York City are generally authorized or obligated by law or
executive order to close.

         5. The Company agrees with each of the Underwriters:

         (a) To prepare the Prospectus in a form approved by you and to file
such Prospectus pursuant to Rule 424(b) under the Act not later than the
Commission's close of business on the second business day following the
execution and delivery of this Agreement, or, if applicable, such earlier time
as may be required by Rule 430A(a)(3) under the Act; to make no further
amendment or any supplement to the Registration Statement or Prospectus prior to
such Time of Delivery which shall be disapproved by you promptly after
reasonable notice thereof; to advise you, promptly after it receives notice
thereof, of the time when any amendment to the Registration Statement has been
filed or becomes effective or any supplement to the Prospectus or any amended
Prospectus has been filed and to furnish you with copies thereof; to file
promptly all reports and any definitive proxy or information statements required
to be filed by the Company with the Commission pursuant to Section 13(a), 13(c),
14 or 15(d) of the Exchange Act subsequent to the date of the Prospectus and for
so long as the delivery of a prospectus is required in connection with the
offering or sale of the Securities; to advise you, promptly after it receives
notice thereof, of the issuance by the Commission of any stop order or of any
order preventing or suspending the use of any Preliminary Prospectus or the
Prospectus, of the suspension of the qualification of the Securities for
offering or sale in any jurisdiction, of the initiation or threatening of any
proceeding for any such purpose, or of any request by the Commission for the
amending or supplementing of the Registration Statement or Prospectus or for
additional information; and, in the event of the issuance of any stop order or
of any order preventing or suspending the use of any Preliminary Prospectus or
the Prospectus or suspending any such qualification, to promptly use its best
efforts to obtain the withdrawal of such order;


                                      -10-

<PAGE>


         (b) Promptly from time to time to take such action as you may
reasonably request to qualify the Securities for offering and sale under the
securities laws of such jurisdictions as you may reasonably request and to
comply with such laws so as to permit the continuance of sales and dealings
therein in such jurisdictions for as long as may be necessary to complete the
distribution of the Securities, provided that in connection therewith the
Company shall not be required to qualify as a foreign corporation or to file a
general consent to service of process in any jurisdiction;

         (c) Prior to 10:00 a.m., New York City time, on the New York Business
Day next succeeding the date of this Agreement and from time to time, to furnish
the Underwriters with written and electronic copies of the Prospectus in New
York City in such quantities as you may reasonably request, and, if the delivery
of a prospectus is required under the Act at any time prior to the expiration of
nine months after the time of issue of the Prospectus in connection with the
offering or sale of the Securities and if at such time any event shall have
occurred as a result of which the Prospectus as then amended or supplemented
would include an untrue statement of a material fact or omit to state any
material fact necessary in order to make the statements therein, in light of the
circumstances under which they were made when such Prospectus is delivered, not
misleading, or, if for any other reason it shall be necessary during such same
period to amend or supplement the Prospectus or to file under the Exchange Act
any document incorporated by reference in the Prospectus in order to comply with
the Act, the Exchange Act or the Trust Indenture Act, to notify you and upon
your request to file such document and to prepare and furnish without charge to
each Underwriter and to any dealer in securities as many written and electronic
copies as you may from time to time reasonably request of an amended Prospectus
or a supplement to the Prospectus which will correct such statement or omission
or effect such compliance; and in case any Underwriter is required under the Act
to deliver a prospectus in connection with sales of any of the Securities at any
time nine months or more after the time of issue of the Prospectus, upon your
request but at the expense of such Underwriter, to prepare and deliver to such
Underwriter as many written and electronic copies as you may request of an
amended or supplemented Prospectus complying with Section 10(a)(3) of the Act;

         (d) To make generally available to its securityholders as soon as
practicable, but in any event not later than eighteen months after the effective
date of the Registration Statement (as defined in Rule 158(c) under the Act), an
earnings statement of the Company and its subsidiaries (which need not be
audited) complying with Section 11(a) of the Act and the rules and regulations
of the Commission thereunder (including, at the option of the Company, Rule
158);

         (e) During the period beginning from the date hereof and continuing to
and including the date 90 days after the date of the Prospectus, not to offer,
sell, contract to sell or otherwise dispose of, except as provided hereunder any
securities of the Company that are substantially similar to the Securities;

         (f) To furnish to the holders of the Securities within the time period
prescribed by the Exchange Act, an annual report (including a balance sheet and
statements of income, stockholders' equity and cash flows of the Company and its
consolidated subsidiaries certified by independent public accountants) and,
within the time period prescribed by the Exchange Act, (beginning with the
fiscal quarter ending after the effective date of the Registration Statement),
consolidated summary financial information of the Company and its subsidiaries
for such quarter in reasonable detail;


                                      -11-

<PAGE>


         (g) During a period of five years from the effective date of the
Registration Statement, to furnish to you upon request copies of all reports or
other communications (financial or other) furnished to stockholders, and to
deliver to you (i) as soon as they are available, copies of any reports and
financial statements furnished to or filed with the Commission or any national
securities exchange on which the Securities or any class of securities of the
Company is listed; and (ii) subject to your obligations under applicable law,
such additional information concerning the business and financial condition of
the Company as you may from time to time reasonably request (such financial
statements to be on a consolidated basis to the extent the accounts of the
Company and its subsidiaries are consolidated in reports furnished to its
stockholders generally or to the Commission);

         (h) To use the net proceeds received by it from the sale of the
Securities pursuant to this Agreement in the manner specified in the Prospectus
under the caption "Use of Proceeds" and in a manner such that the Company will
not become an "investment company" as that term is defined in the Investment
Company Act;

         (i) If the Company elects to rely upon Rule 462(b), the Company shall
file a Rule 462(b) Registration Statement with the Commission in compliance with
Rule 462(b) by 10:00 P.M., Washington, D.C. time, on the date of this Agreement,
and the Company shall at the time of filing either pay to the Commission the
filing fee for the Rule 462(b) Registration Statement or give irrevocable
instructions for the payment of such fee pursuant to Rule 111(b) under the Act;

         (k) To reserve and keep available at all times, free of preemptive
rights, shares of Stock for the purpose of enabling the Company to satisfy any
obligations to issue shares of its Stock upon conversion of the Securities;

         (l) Not to grant options, warrants or other rights to purchase shares
of Stock that would become exercisable (other than in connection with a "change
in control" of the Company) during the period beginning on the date hereof and
continuing to and including the date 90 days after the date of the Prospectus,
other than options under the Company's 2000 Employee Stock Purchase Plan and
such options, warrants or other rights granted to persons who, prior to such
grant, execute agreements in the form set forth in Exhibit A;

         (m) Upon request of any Underwriter to furnish, or cause to be
furnished, to such Underwriter an electronic version of the Company's
trademarks, servicemarks and corporate logo for use on the website, if any,
operated by such Underwriter for the purpose of facilitating the on-line
offering of the Shares (the "License"); PROVIDED, HOWEVER, that the License
shall be non-exclusive, shall not provide the right to sub-license, shall be
limited solely for the purpose described above, is granted without any fee, may
not be assigned or transferred to any Person and shall terminate upon
consummation of the public offering contemplated by the Prospectus.

         6. The Company covenants and agrees with the several Underwriters that
the Company will pay or cause to be paid the following: (i) the fees,
disbursements and expenses of the Company's counsel and accountants in
connection with the registration of the Securities under the Act and all other
expenses in connection with the preparation, printing and filing of the
Registration Statement, any Preliminary Prospectus and the Prospectus and
amendments and supplements thereto and the mailing and delivering of copies
thereof to the Underwriters and dealers; (ii) the cost of printing or producing
any Agreement among Underwriters, this Agreement, the Indenture, the Blue Sky
Memoranda, closing documents (including any compilations thereof) and any other
documents in


                                      -12-

<PAGE>


connection with the offering, purchase, sale and delivery of the Securities;
(iii) all expenses in connection with the qualification of the Securities for
offering and sale under state securities laws as provided in Section 5(b)
hereof, including the fees and disbursements of counsel for the Underwriters in
connection with such qualification and in connection with the Blue Sky
Memoranda; (iv) any fees charged by securities rating services for rating the
Securities; (v) the filing fees incident to securing any required review by the
National Association of Securities Dealers, Inc. of the terms of the sale of the
Securities; (vi) the cost of preparing the Securities; (vii) the fees and
expenses of the Trustee and any agent of the Trustee and the fees and
disbursements of counsel for the Trustee in connection with the Indenture and
the Securities; and (viii) all other costs and expenses incident to the
performance of its obligations hereunder which are not otherwise specifically
provided for in this Section. It is understood, however, that, (x) except as
provided in this Section, and Sections 8 and 11 hereof, the Underwriters will
pay all of their own costs and expenses, including the fees of their counsel,
transfer taxes on resale of any of the Securities by them, and any advertising
expenses connected with any offers they may make, and (y) other than with
respect to filing or similar fees, the maximum liability of the Company under
clauses (a)(ii) and (a)(iii) above shall be $10,000.

         7. The obligations of the Underwriters hereunder shall be subject, in
their discretion, to the condition that all representations and warranties and
other statements of the Company herein are, at and as of such Time of Delivery,
true and correct, the condition that the Company shall have performed all of its
obligations hereunder theretofore to be performed, and the following additional
conditions:

         (a) The Prospectus shall have been filed with the Commission pursuant
to Rule 424(b) within the applicable time period prescribed for such filing by
the rules and regulations under the Act and in accordance with Section 5(a)
hereof; if the Company has elected to rely upon Rule 462(b), the Rule 462(b)
Registration Statement shall have become effective by 10:00 P.M., Washington,
D.C. time, on the date of this Agreement; no stop order suspending the
effectiveness of the Registration Statement or any part thereof shall have been
issued and no proceeding for that purpose shall have been initiated or
threatened by the Commission; and all requests for additional information on the
part of the Commission shall have been complied with to your reasonable
satisfaction;

         (b)           , counsel for the Underwriters, shall have furnished to
you such written opinion or opinions (a draft of each such opinion is attached
as Annex II(a) hereto), dated such Time of Delivery, with respect to the matters
covered in paragraphs (i), (ii), (v), (vi), (x), and (xii) of subsection (c)
below as well as such other related matters as you may reasonably request, and
such counsel shall have received such papers and information as they may
reasonably request to enable them to pass upon such matters;

         (c) Bingham Dana LLP, counsel for the Company, shall have furnished to
you their written opinion (a draft of such opinion is attached as Annex II(b)
hereto), dated such Time of Delivery, in form and substance satisfactory to you,
to the effect that:

         (i) The Company has been duly incorporated and is validly existing as a
corporation in good standing under the laws of the State of Delaware, with
corporate power and authority to own its properties and conduct its business as
described in the Prospectus;

         (ii) The Company has an authorized capitalization as set forth in the
Prospectus; in addition: (i) all of the shares of the Company's common stock,
par value $0.001 per share ("COMMON


                                      -13-

<PAGE>


STOCK"), that were outstanding immediately following the closing of the
Company's initial public offering on May 31, 2000, have been duly authorized and
are validly issued, fully paid and non-assessable; (ii) all of the shares of
Common Stock that were issued pursuant to the Company's acquisition of TTI,
which acquisition closed on January 18, 2001, have been duly authorized and are
validly issued, fully paid and non-assessable; (iii) the _________shares of
Common Stock to be delivered by the Company to the Underwriters, pursuant to
that certain Underwriting Agreement, dated as of _________, ___, by and among
the Company and the Underwriters, with respect to the offer and sale of such
shares of Common Stock (the "EQUITY UNDERWRITING AGREEMENT"), at each Time of
Delivery (as such term is defined in the Equity Underwriting Agreement") have
been duly authorized and, assuming due execution and delivery of the Equity
Underwriting Agreement by all of the Underwriters and compliance by all of the
Underwriters with the terms thereof, and assuming payment in full by the
Underwriters for all of such shares of Common Stock as provided in the Equity
Underwriting Agreement, such shares of Common Stock shall be validly issued,
fully paid and non-assessable; and (iv) to such counsel's knowledge, all shares
of capital stock of the Company that are, as of the date hereof, issued and
outstanding, other than those shares of capital stock described in clauses (i)
through (iii) of this paragraph 2, have been duly authorized and are validly
issued, fully paid and non-assessable;

         (iii) The Company is duly qualified as a foreign corporation for the
transaction of business and is in good standing as a foreign corporation under
the laws of the Commonwealth of Massachusetts;

         (iv) To the best of such counsel's knowledge and other than as set
forth in the Prospectus, there are no legal or governmental proceedings pending
to which the Company or any of its subsidiaries is a party or of which any
property of the Company or any of its subsidiaries is the subject which, if
determined adversely to the Company or any of its subsidiaries, would
individually or in the aggregate be reasonably expected to have a material
adverse effect on the business, assets, management, financial position or
results of operations of the Company and its subsidiaries taken as a whole; and,
to such counsel's knowledge but without having investigated any governmental
records or court dockets, no such proceedings are overtly threatened by
governmental authorities or others;

         (v) The Company has full corporate power and authority to enter into
this Agreement and this Agreement has been duly authorized, executed and
delivered by the Company;

         (vi) The Securities have been duly authorized, executed, issued and
delivered by the Company and authenticated by the Trustee and constitute valid
and legally binding obligations of the Company, enforceable against the Company
in accordance with their respective terms (except that such counsel expresses no
opinion as to the enforceability of any indemnification and contribution
provisions thereof); and the Securities and the Indenture conform as to legal
matters, in all material respects, to the description thereof set forth in the
Prospectus under the caption "Description of Notes;"

         (vii) The Indenture has been duly authorized by all necessary corporate
action on the part of the Company and its stockholders, if necessary, and has
been duly executed and delivered by the Company and constitutes a valid and
binding agreement of the Company, enforceable against the Company in accordance
with its terms (except that such counsel expresses no opinion as to the
enforceability of any indemnification and contribution provisions thereof); and
the Indenture has been duly qualified under the Trust Indenture Act of 1939, as
amended (the "TRUST INDENTURE ACT");


                                      -14-

<PAGE>


         (viii) The issue and sale of the Securities to be delivered at such
Time of Delivery by the Company and the compliance by the Company with all of
the provisions of the Securities, the Indenture, and this Agreement and the
consummation of the transactions herein and therein contemplated will not (a)
result in a breach or violation of any of the terms or provisions of, or
constitute a default under, any indenture, mortgage, deed of trust, loan
agreement or other agreement or instrument known to such counsel to which the
Company or any of its subsidiaries is a party or by which the Company or any of
its subsidiaries is bound or to which any of the property or assets of the
Company or any of its subsidiaries is subject, (b) result in any violation of
the provisions of the Charter or By-laws or any federal or Massachusetts
statute, rule or regulation, or (c) to such counsel's knowledge, violate any
order known to such counsel of any federal or Massachusetts court or
governmental agency or body having jurisdiction over the Company or any of its
subsidiaries or any of their properties;

         (ix) No consent, approval, authorization, order, filing, registration
or qualification of or with any federal or Massachusetts court or governmental
agency or body is required for the issue and sale of the Securities to be issued
at such Time of Delivery or the consummation by the Company of the transactions
contemplated by this Agreement or the Indenture, except for the registration
under the Act of the Securities or as is required under the Trust Indenture Act,
and such consents, approvals, authorizations, filings, registrations or
qualifications as may be required under state securities or Blue Sky laws in
connection with the purchase and distribution of the Securities by the
Underwriters (as to which such counsel renders no opinion);

         (x) The statements set forth in the Prospectus under the caption
"Description of Notes," insofar as they purport to summarize provisions of the
Securities and the terms of the Stock are accurate summaries in all material
respects of the provisions or terms purported to be summarized therein, and the
statements set forth in the Prospectus under the captions "Certain United States
Federal Income Tax Considerations," "Shares Eligible for Future Sale" and
"Underwriting," insofar as they purport to describe the provisions of the laws
and the underwriting agreement and lock-up agreements referred to therein, are
accurate and complete in all material respects;

         (xi) The Company is not an "investment company," as such term is
defined in the Investment Company Act and, immediately after giving effect to
the transactions contemplated by this Agreement, will not be an "investment
company;"

         (xii) The Registration Statement, as of its effective date, and the
Prospectus, as of its date (other than the financial statements and related
schedules and other financial and accounting data therein, as to which such
counsel expresses no opinion) comply as to form in all material respects with
the requirements of the Act and the Trust Indenture Act and the rules and
regulations thereunder; and such counsel does not know of any contracts or other
documents of a character required to be filed as an exhibit to the Registration
Statement or required to be described in the Registration Statement or the
Prospectus which are not filed or described as required;

         (xiii) The documents incorporated by reference into the Prospectus as
of its date, or any amendment or supplement thereto made by the Company prior to
such Time of Delivery (other than the financial statements and related schedules
and other financial and accounting data therein, as to which such counsel
expresses no opinion) comply as to form in all material respects with the
requirements of the Securities Exchange Act of 1934, as amended, and the rules
and regulations thereunder; and


                                      -15-

<PAGE>


         (xiv) The Registration Statement has become effective under the Act. To
the best of such counsel's knowledge, no stop order suspending the effectiveness
of the Registration Statement has been issued by the Commission nor has any
proceeding been instituted for that purpose under the Act. The Prospectus has
been filed with the Commission pursuant to Rule 424(b) of the rules and
regulations under the Act within the time period required thereby.

         (d) On the date of the Prospectus at a time prior to the execution of
this Agreement, at 9:30 a.m., New York City time, on the effective date of any
post-effective amendment to the Registration Statement filed subsequent to the
date of this Agreement and also at each Time of Delivery, Arthur Andersen LLP
shall have furnished to you a letter or letters, dated the respective dates of
delivery thereof, in form and substance satisfactory to you, to the effect set
forth in Annex I hereto (the executed copy of the letter delivered prior to the
execution of this Agreement is attached as Annex I(a) hereto and a draft of the
form of letter to be delivered on the effective date of any post-effective
amendment to the Registration Statement and as of each Time of Delivery is
attached as Annex I(b) hereto);

         (e) (i) Neither the Company nor any of its subsidiaries shall have
sustained since the date of the latest audited financial statements included in
the Prospectus any loss or interference with its business from fire, explosion,
flood or other calamity, whether or not covered by insurance, or from any labor
dispute or court or governmental action, order or decree, otherwise than as set
forth or contemplated in the Prospectus, and (ii) since the respective dates as
of which information is given in the Prospectus there shall not have been any
change in the capital stock or long-term debt of the Company or any of its
subsidiaries or any change, or any development involving a prospective change,
in or affecting the business, assets, management, financial position,
stockholders' equity or results of operations of the Company and its
subsidiaries taken as a whole, otherwise than as set forth or contemplated in
the Prospectus, the effect of which, in any such case described in clause (i) or
(ii), is in the judgment of the Representatives so material and adverse as to
make it impracticable or inadvisable to proceed with the public offering or the
delivery of the Securities being issued at such Time of Delivery on the terms
and in the manner contemplated in the Prospectus;

         (f) On or after the date hereof: (i) no downgrading shall have occurred
in the rating accorded the Company's debt securities by any "nationally
recognized statistical rating organization", as that term is defined by the
Commission for purposes of Rule 436(g)(2) under the Act, and (ii) no such
organization shall have publicly announced that it has under surveillance or
review, with possible negative implications, its rating of any of the Company's
debt securities;

         (g) On or after the date hereof there shall not have occurred any of
the following: (i) a suspension or material limitation in trading in securities
generally on the New York Stock Exchange or on NASDAQ; (ii) a suspension or
material limitation in trading in the Company's securities on NASDAQ; (iii) a
general moratorium on commercial banking activities declared by either Federal
or New York or Massachusetts state authorities; (iv) the occurrence of any
material adverse change in the existing, financial, political or economic
conditions of the United States or elsewhere which, in the judgment of the
Representatives, would materially and adversely affect the financial markets or
the markets for the Securities and other debt securities or the market for or
any equity securities; or (v) the outbreak or escalation of hostilities
involving the United States or the declaration by the United States of a
national emergency or war, if the effect of any such event specified in this
clause (v) in the judgment of the Representatives makes it impracticable or
inadvisable to proceed with the public


                                      -16-

<PAGE>


offering or the delivery of the Securities being issued at such Time of Delivery
on the terms and in the manner contemplated in the Prospectus;

         (h) The Company has obtained and delivered to the Underwriters executed
copies of an agreement from each of the directors, executive officers and other
stockholders of the Company listed on Schedule II hereto, in form and substance
previously agreed to by you and attached hereto as Exhibit A;

         (i) The Company shall have complied with the provisions of Section 5(c)
hereof with respect to the furnishing of prospectuses on the New York Business
Day next succeeding the date of this Agreement;

         (j) Beachcroft Wansbroughs, local counsel for Sonus Networks Limited, a
United Kingdom corporation (the "UK SUBSIDIARY"), shall have furnished to you
their written opinion (a draft of such opinion is attached as Annex II(c)
hereto), dated such Time of Delivery, in form and substance satisfactory to you,
to the effect that:

                  (i) The UK Subsidiary has been duly incorporated and is
         validly existing as a corporation in good standing under the laws of
         the United Kingdom; and

                  (ii) All of the issued shares of capital stock of the UK
         Subsidiary have been duly authorized and validly issued, are fully paid
         and nonassessable, and are owned directly or indirectly by the Company,
         and, to the knowledge of such counsel, free and clear of all liens,
         encumbrances, equities or claims.

         (k) Singapore counsel reasonably satisfactory to the Underwriters, as
local counsel for Sonus Networks Pte Ltd, a Singapore corporation (the
"SINGAPORE SUBSIDIARY"), shall have furnished to you their written opinion (a
draft of such opinion is attached as Annex II(e) hereto), dated such Time of
Delivery, in form and substance satisfactory to you, to the effect that:

                  (i) The Singapore Subsidiary has been duly incorporated and is
         validly existing as a corporation in good standing under the laws of
         the United Kingdom; and

                  (ii) All of the issued shares of capital stock of the
         Singapore Subsidiary have been duly authorized and validly issued, are
         fully paid and nonassessable, and are owned directly or indirectly by
         the Company and, to the knowledge of such counsel, free and clear of
         all liens, encumbrances, equities or claims.

         (l) Texas counsel reasonable satisfactory to the Underwriters, as local
counsel for TTI, a Texas corporation, shall have furnished to you their written
opinion (a draft of such opinion is attached as Annex II(d) hereto), dated such
Time of Delivery, in form and substance satisfactory to you, to the effect that:

                  (i) TTI has been duly incorporated and is validly existing as
         a corporation in good standing under the laws of the State of Texas;
         and

                  (ii) All of the issued shares of capital stock of the TTI have
         been duly authorized and validly issued, are fully paid and
         nonassessable, and are owned directly or indirectly by


                                      -17-

<PAGE>


         the Company, free and clear of all liens, encumbrances, equities or
         claims to the knowledge of such counsel.

         (m) The Company shall have furnished or caused to be furnished to you
at such Time of Delivery certificates of officers of the Company satisfactory to
you as to the accuracy of the representations and warranties of the Company
herein at and as of such Time of Delivery, as to the performance by the Company
of all of its obligations hereunder to be performed at or prior to such Time of
Delivery, as to the matters set forth in subsections (a) and (e) of this Section
and as to such other matters as you may reasonably request.

         8. (a) The Company will indemnify and hold harmless each Underwriter
against any losses, claims, damages or liabilities, joint or several, to which
such Underwriter may become subject, under the Act or otherwise, insofar as such
losses, claims, damages or liabilities (or actions in respect thereof) arise out
of or are based upon an untrue statement or alleged untrue statement of a
material fact contained in any Preliminary Prospectus, the Registration
Statement or the Prospectus, or any amendment or supplement thereto, or arise
out of or are based upon the omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, and will reimburse each Underwriter for any legal or
other expenses reasonably incurred by such Underwriter in connection with
investigating or defending any such action or claim as such expenses are
incurred; PROVIDED, HOWEVER, that the Company shall not be liable in any such
case to the extent that any such loss, claim, damage or liability arises out of
or is based upon an untrue statement or alleged untrue statement or omission or
alleged omission made in any Preliminary Prospectus, the Registration Statement
or the Prospectus or any such amendment or supplement in reliance upon and in
conformity with written information furnished to the Company by any Underwriter
through                  expressly for use therein.

         (b) Each Underwriter will indemnify and hold harmless the Company
against any losses, claims, damages or liabilities to which the Company may
become subject, under the Act or otherwise, insofar as such losses, claims,
damages or liabilities (or actions in respect thereof) arise out of or are based
upon an untrue statement or alleged untrue statement of a material fact
contained in any Preliminary Prospectus, the Registration Statement or the
Prospectus, or any amendment or supplement thereto, or arise out of or are based
upon the omission or alleged omission to state therein a material fact required
to be stated therein or necessary to make the statements therein not misleading,
in each case to the extent, but only to the extent, that such untrue statement
or alleged untrue statement or omission or alleged omission was made in any
Preliminary Prospectus, the Registration Statement or the Prospectus or any such
amendment or supplement in reliance upon and in conformity with written
information furnished to the Company by such Underwriter through 
expressly for use therein; and will reimburse the Company for any legal or
other expenses reasonably incurred by the Company in connection with
investigating or defending any such action or claim as such expenses are
incurred.

         (c) Promptly after receipt by an indemnified party under subsection (a)
or (b) above of notice of the commencement of any action, such indemnified party
shall, if a claim in respect thereof is to be made against the indemnifying
party under such subsection, notify the indemnifying party in writing of the
commencement thereof; but the omission so to notify the indemnifying party shall
not relieve it from any liability which it may have to any indemnified party
otherwise than under such subsection. In case any such action shall be brought
against any indemnified party and it shall notify the


                                      -18-

<PAGE>


indemnifying party of the commencement thereof, the indemnifying party shall be
entitled to participate therein and, to the extent that it shall wish, jointly
with any other indemnifying party similarly notified, to assume the defense
thereof, with counsel satisfactory to such indemnified party (who shall not,
except with the consent of the indemnified party, be counsel to the indemnifying
party), and, after notice from the indemnifying party to such indemnified party
of its election so to assume the defense thereof, the indemnifying party shall
not be liable to such indemnified party under such subsection for any legal
expenses of other counsel or any other expenses, in each case subsequently
incurred by such indemnified party, in connection with the defense thereof other
than reasonable costs of investigation. No indemnifying party shall, without the
written consent of the indemnified party, effect the settlement or compromise
of, or consent to the entry of any judgment with respect to, any pending or
threatened action or claim in respect of which indemnification or contribution
may be sought hereunder (whether or not the indemnified party is an actual or
potential party to such action or claim) unless such settlement, compromise or
judgment (i) includes an unconditional release of the indemnified party from all
liability arising out of such action or claim and (ii) does not include a
statement as to or an admission of fault, culpability or a failure to act, by or
on behalf of any indemnified party.

         (d) If the indemnification provided for in this Section 8 is
unavailable to or insufficient to hold harmless an indemnified party under
subsection (a) or (b) above in respect of any losses, claims, damages or
liabilities (or actions in respect thereof) referred to therein, then each
indemnifying party shall contribute to the amount paid or payable by such
indemnified party as a result of such losses, claims, damages or liabilities (or
actions in respect thereof) in such proportion as is appropriate to reflect the
relative benefits received by the Company on the one hand and the Underwriters
on the other from the offering of the Securities. If, however, the allocation
provided by the immediately preceding sentence is not permitted by applicable
law or if the indemnified party failed to give the notice required under
subsection (c) above, then each indemnifying party shall contribute to such
amount paid or payable by such indemnified party in such proportion as is
appropriate to reflect not only such relative benefits but also the relative
fault of the Company on the one hand and the Underwriters on the other in
connection with the statements or omissions which resulted in such losses,
claims, damages or liabilities (or actions in respect thereof), as well as any
other relevant equitable considerations. The relative benefits received by the
Company on the one hand and the Underwriters on the other shall be deemed to be
in the same proportion as the total net proceeds from the offering (before
deducting expenses) received by the Company bear to the total underwriting
discounts and commissions received by the Underwriters, in each case as set
forth in the table on the cover page of the Prospectus. The relative fault shall
be determined by reference to, among other things, whether the untrue or alleged
untrue statement of a material fact or the omission or alleged omission to state
a material fact relates to information supplied by the Company on the one hand
or the Underwriters on the other and the parties' relative intent, knowledge,
access to information and opportunity to correct or prevent such statement or
omission. The Company and the Underwriters agree that it would not be just and
equitable if contribution pursuant to this subsection (d) were determined by PRO
RATA allocation (even if the Underwriters were treated as one entity for such
purpose) or by any other method of allocation which does not take account of the
equitable considerations referred to above in this subsection (d). The amount
paid or payable by an indemnified party as a result of the losses, claims,
damages or liabilities (or actions in respect thereof) referred to above in this
subsection (d) shall be deemed to include any legal or other expenses reasonably
incurred by such indemnified party in connection with investigating or defending
any such action or claim. Notwithstanding the provisions of this subsection (d),
no Underwriter shall be required to contribute any amount in excess of the
amount by which the total price at which the


                                      -19-

<PAGE>


Securities underwritten by it and distributed to the public were offered to the
public exceeds the amount of any damages which such Underwriter has otherwise
been required to pay by reason of such untrue or alleged untrue statement or
omission or alleged omission. No person guilty of fraudulent misrepresentation
(within the meaning of Section 11(f) of the Act) shall be entitled to
contribution from any person who was not guilty of such fraudulent
misrepresentation. The Underwriters' obligations in this subsection (d) to
contribute are several in proportion to their respective underwriting
obligations and not joint.

         (e) The obligations of the Company under this Section 8 shall be in
addition to any liability which the Company may otherwise have and shall extend,
upon the same terms and conditions, to each person, if any, who controls any
Underwriter within the meaning of the Act; and the obligations of the
Underwriters under this Section 8 shall be in addition to any liability which
the respective Underwriters may otherwise have and shall extend, upon the same
terms and conditions, to each officer and director of the Company (including any
person who, with his or her consent, is named in the Registration Statement as
about to become a director of the Company) and to each person, if any, who
controls the Company within the meaning of the Act.

         9. (a) If any Underwriter shall default in its obligation to purchase
the Securities which it has agreed to purchase hereunder at a Time of Delivery,
you may in your discretion arrange for you or another party or other parties to
purchase such Securities on the terms contained herein. If within thirty-six
hours after such default by any Underwriter you do not arrange for the purchase
of such Securities, then the Company shall be entitled to a further period of
thirty-six hours within which to procure another party or other parties
satisfactory to you to purchase such Securities on such terms. In the event
that, within the respective prescribed periods, you notify the Company that you
have so arranged for the purchase of such Securities, or the Company notifies
you that it has so arranged for the purchase of such Securities, you or the
Company shall have the right to postpone such Time of Delivery for a period of
not more than seven days, in order to effect whatever changes may thereby be
made necessary in the Registration Statement or the Prospectus, or in any other
documents or arrangements, and the Company agrees to file promptly any
amendments to the Registration Statement or the Prospectus which in your opinion
may thereby be made necessary. The term "Underwriter" as used in this Agreement
shall include any person substituted under this Section with like effect as if
such person had originally been a party to this Agreement with respect to such
Securities.

         (b) If, after giving effect to any arrangements for the purchase of the
Securities of a defaulting Underwriter or Underwriters by you and the Company as
provided in subsection (a) above, the aggregate principal amount of such
Securities which remains unpurchased does not exceed one-eleventh of the
aggregate principal amount of all the Securities to be purchased at such Time of
Delivery, then the Company shall have the right to require each non-defaulting
Underwriter to purchase the principal amount of Securities which such
Underwriter agreed to purchase hereunder at such Time of Delivery and, in
addition, to require each non-defaulting Underwriter to purchase its pro rata
share (based on the principal amount of Securities which such Underwriter agreed
to purchase hereunder) of the Securities of such defaulting Underwriter or
Underwriters for which such arrangements have not been made; but nothing herein
shall relieve a defaulting Underwriter from liability for its default.

         (c) If, after giving effect to any arrangements for the purchase of the
Securities of a defaulting Underwriter or Underwriters by you and the Company as
provided in subsection (a) above,


                                      -20-

<PAGE>


the aggregate principal amount of Securities which remains unpurchased exceeds
one-eleventh of the aggregate principal amount of all the Securities to be
purchased at such Time of Delivery, or if the Company shall not exercise the
right described in subsection (b) above to require non-defaulting Underwriters
to purchase Securities of a defaulting Underwriter or Underwriters, then this
Agreement (or, with respect to the Second Time of Delivery, the obligation of
the Underwriters to purchase and of the Company to sell the Optional Securities)
shall thereupon terminate, without liability on the part of any non-defaulting
Underwriter or the Company, except for the expenses to be borne by the Company
and the Underwriters as provided in Section 6 hereof and the indemnity and
contribution agreements in Section 8 hereof; but nothing herein shall relieve a
defaulting Underwriter from liability for its default.

         10. The respective indemnities, agreements, representations, warranties
and other statements of the Company and the several Underwriters, as set forth
in this Agreement or made by or on behalf of them, respectively, pursuant to
this Agreement, shall remain in full force and effect, regardless of any
investigation (or any statement as to the results thereof) made by or on behalf
of any Underwriter or any controlling person of any Underwriter, or the Company,
or any officer or director or controlling person of the Company, and shall
survive delivery of and payment for the Securities.

         11. If this Agreement shall be terminated pursuant to Section 9 hereof,
the Company shall not then be under any liability to any Underwriter except as
provided in Sections 6 and 8 hereof; but, if for any other reason, any
Securities are not delivered by or on behalf of the Company as provided herein,
the Company will reimburse the Underwriters through you for all out-of-pocket
expenses approved in writing by you, including fees and disbursements of
counsel, reasonably incurred by the Underwriters in making preparations for the
purchase, sale and delivery of the Securities, but the Company shall then be
under no further liability to any Underwriter except as provided in Sections 6
and 8 hereof.

         12. In all dealings hereunder, you shall act on behalf of each of the
Underwriters, and the parties hereto shall be entitled to act and rely upon any
statement, request, notice or agreement on behalf of any Underwriter made or
given by you jointly or by                          on behalf of you as the
representatives.

         All statements, requests, notices and agreements hereunder shall be 
in writing, and if to the Underwriters shall be delivered or sent by mail, 
telex or facsimile transmission to you as the representatives in care of      
            ; and if to the Company shall be delivered or sent by mail, telex 
or facsimile transmission to the address of the Company set forth in the 
Registration Statement, Attention: Secretary; provided, however, that any 
notice to an Underwriter pursuant to Section 8(c) hereof shall be delivered 
or sent by mail, telex or facsimile transmission to such Underwriter at its 
address set forth in its Underwriters' Questionnaire, or telex constituting 
such Questionnaire, which address will be supplied to the Company by you upon 
request. Any such statements, requests, notices or agreements shall take 
effect upon receipt thereof.

         13. This Agreement shall be binding upon, and inure solely to the
benefit of, the Underwriters, the Company and, to the extent provided in
Sections 8 and 10 hereof, the officers and directors of the Company and each
person who controls the Company or any Underwriter, and their respective heirs,
executors, administrators, successors and assigns, and no other person shall


                                      -21-

<PAGE>


acquire or have any right under or by virtue of this Agreement. No purchaser of
any of the Securities from any Underwriter shall be deemed a successor or assign
by reason merely of such purchase.

         14. Time shall be of the essence of this Agreement. As used herein, the
term "business day" shall mean any day when the Commission's office in
Washington, D.C. is open for business.

         15. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE
WITH THE LAWS OF THE STATE OF NEW YORK.

         16. This Agreement may be executed by any one or more of the parties
hereto in any number of counterparts, each of which shall be deemed to be an
original, but all such respective counterparts shall together constitute one and
the same instrument.

         17. The Company is authorized, subject to applicable law, to disclose
any and all aspects of this potential transaction that are necessary to support
any U.S. federal income tax benefits expected to be claimed with respect to such
transaction, without the Underwriters imposing any limitation of any kind.


                                      -22-

<PAGE>


         If the foregoing is in accordance with your understanding, please sign
and return to us one for the Company and each of the Representatives plus one
for each counsel counterparts hereof, and upon the acceptance hereof by you, on
behalf of each of the Underwriters, this letter and such acceptance hereof shall
constitute a binding agreement between each of the Underwriters and the Company.
It is understood that your acceptance of this letter on behalf of each of the
Underwriters is pursuant to the authority set forth in a form of Agreement among
Underwriters, the form of which shall be submitted to the Company for
examination upon request, but without warranty on your part as to the authority
of the signers thereof.


                                             Very truly yours,


                                             SONUS NETWORKS, INC.


                                             By: 
                                                 ---------------------------
                                                 Name:
                                                 Title:


Accepted as of the date hereof:



Co-Representatives


By: 
    ----------------------------------



(on behalf of each of the Underwriters)




                                      -23-

<PAGE>


                                   SCHEDULE I


<TABLE>
<CAPTION>

                                                                                        PRINCIPAL
                                                                  PRINCIPAL             AMOUNT OF
                                                                  AMOUNT OF             OPTIONAL SECURITIES
                                                                  FIRM SECURITIES       TO BE PURCHASED
                                                                  TO BE                 IF MAXIMUM OPTION
UNDERWRITER                                                       PURCHASED             EXERCISED
-----------                                                       ---------             ---------
<S>                                                               <C>                   <C>
..............................................................    $                     $
..............................................................
..............................................................
..............................................................
[NAMES OF OTHER UNDERWRITERS].................................
                                                                  -----------           ----------
                  Total.......................................    $                     $
                                                                  ===========           ==========
</TABLE>



                                      -24-

<PAGE>


                                   SCHEDULE II


                               LOCK-UP AGREEMENTS




                                      -25-

<PAGE>



                                    EXHIBIT A




                                      -26-

<PAGE>


                                     ANNEX I


                             FORM OF COMFORT LETTER

         Pursuant to Section 7(d) of the Underwriting Agreement, the accountants
shall furnish letters to the Underwriters to the effect that:


               (i) They are independent certified public accountants with
         respect to the Company and its subsidiaries within the meaning of the
         Act and the applicable published rules and regulations thereunder;

               (ii) In their opinion, the financial statements and any
         supplementary financial information and schedules (and, if applicable,
         financial forecasts and/or pro forma financial information) examined by
         them and included or incorporated by reference in the Registration
         Statement or the Prospectus comply as to form in all material respects
         with the applicable accounting requirements of the Act or the Exchange
         Act, as applicable, and the related published rules and regulations
         thereunder; and, if applicable, they have made a review in accordance
         with standards established by the American Institute of Certified
         Public Accountants of the consolidated interim financial statements,
         selected financial data, pro forma financial information, financial
         forecasts and/or condensed financial statements derived from audited
         financial statements of the Company for the periods specified in such
         letter, as indicated in their reports thereon, copies of which have
         been furnished to the representatives of the Underwriters (the
         "Representatives") and are attached hereto;

               (iii) They have made a review in accordance with standards
         established by the American Institute of Certified Public Accountants
         of the unaudited condensed consolidated statements of income,
         consolidated balance sheets and consolidated statements of cash flows
         included in the Prospectus and/or included in the Company's quarterly
         report on Form 10-Q incorporated by reference into the Prospectus as
         indicated in their reports thereon copies of which are attached hereto;
         and on the basis of specified procedures including inquiries of
         officials of the Company who have responsibility for financial and
         accounting matters regarding whether the unaudited condensed
         consolidated financial statements referred to in paragraph (vi)(A)(i)
         below comply as to form in all material respects with the applicable
         accounting requirements of the Act and the Exchange Act and the related
         published rules and regulations, nothing came to their attention that
         caused them to believe that the unaudited condensed consolidated
         financial statements do not comply as to form in all material respects
         with the applicable accounting requirements of the Act and the Exchange
         Act and the related published rules and regulations;

               (iv) The unaudited selected financial information with respect to
         the consolidated results of operations and financial position of the
         Company for the five most recent fiscal years included in the
         Prospectus and included or incorporated by reference in Item 6 of the
         Company's Annual Report on Form 10-K for the most recent fiscal year
         agrees with the corresponding amounts (after restatement where
         applicable) in the audited consolidated financial statements for such
         five fiscal years which were included or incorporated by reference in
         the Company's Annual Reports on Form 10-K for such fiscal years;

               (v) They have compared the information in the Prospectus under
         selected captions with the disclosure requirements of Regulation S-K
         and on the basis of limited procedures



<PAGE>


         specified in such letter nothing came to their attention as a result of
         the foregoing procedures that caused them to believe that this
         information does not conform in all material respects with the
         disclosure requirements of Items 301, 302, 402 and 503(d),
         respectively, of Regulation S-K;

               (vi) On the basis of limited procedures, not constituting an
         examination in accordance with generally accepted auditing standards,
         consisting of a reading of the unaudited financial statements and other
         information referred to below, a reading of the latest available
         interim financial statements of the Company and its subsidiaries,
         inspection of the minute books of the Company and its subsidiaries
         since the date of the latest audited financial statements included or
         incorporated by reference in the Prospectus, inquiries of officials of
         the Company and its subsidiaries responsible for financial and
         accounting matters and such other inquiries and procedures as may be
         specified in such letter, nothing came to their attention that caused
         them to believe that:

                      (A) (i) the unaudited condensed consolidated statements of
               income, consolidated balance sheets and consolidated statements
               of cash flows included in the Prospectus and/or included or
               incorporated by reference in the Company's Quarterly Reports on
               Form 10-Q incorporated by reference in the Prospectus do not
               comply as to form in all material respects with the applicable
               accounting requirements of the Exchange Act as it applies to Form
               10-Q and the related published rules and regulations, or (ii) any
               material modifications should be made to the unaudited condensed
               consolidated statements of income, consolidated balance sheets
               and consolidated statements of cash flows included in the
               Prospectus or included in the Company's Quarterly Reports on Form
               10-Q incorporated by reference in the Prospectus, for them to be
               conformity with generally accepted accounting principles;

                      (B) any other unaudited income statement data and balance
               sheet items included in the Prospectus do not agree with the
               corresponding items in the unaudited consolidated financial
               statements from which such data and items were derived, and any
               such unaudited data and items were not determined on a basis
               substantially consistent with the basis for the corresponding
               amounts in the audited consolidated financial statements included
               or incorporated by reference in the Company's Annual Report on
               Form 10-K for the most recent fiscal year;

                      (C) the unaudited financial statements which were not
               included in the Prospectus but from which were derived the
               unaudited condensed financial statements referred to in clause
               (A) and any unaudited income statement data and balance sheet
               items included in the Prospectus and referred to in clause (B)
               were not determined on a basis substantially consistent with the
               basis for the audited financial statements included or
               incorporated by reference in the Company's Annual Report on Form
               10-K for the most recent fiscal year;

                      (D) any unaudited pro forma consolidated condensed
               financial statements included or incorporated by reference in the
               Prospectus do not comply as to form in all material respects with
               the applicable accounting requirements of the Act and the
               published rules and regulations thereunder or the pro forma
               adjustments have not been properly applied to the historical
               amounts in the compilation of those statements;

                      (E) as of a specified date not more than five days prior
               to the date of such letter, there have been any changes in the
               consolidated capital stock (other than issuances of



<PAGE>


               capital stock upon exercise of options and stock appreciation
               rights, upon earn-outs of performance shares and upon
               conversions of convertible securities, in each case which were
               outstanding on the date of the latest balance sheet included
               or incorporated by reference in the Prospectus) or any
               increase in the consolidated long-term debt of the Company and
               its subsidiaries, or any decreases in consolidated net current
               assets or stockholders' equity or other items specified by the
               Representatives, or any increases in any items specified by
               the Representatives, in each case as compared with amounts
               shown in the latest balance sheet included or incorporated by
               reference in the Prospectus, except in each case for changes,
               increases or decreases which the Prospectus discloses have
               occurred or may occur or which are described in such letter;
               and

                    (F) for the period from the date of the latest financial
               statements included or incorporated by reference in the
               Prospectus to the specified date referred to in clause (E) there
               were any decreases in consolidated net revenues or operating
               profit or the total or per share amounts of consolidated net
               income or other items specified by the Representatives, or any
               increases in any items specified by the Representatives, in each
               case as compared with the comparable period of the preceding year
               and with any other period of corresponding length specified by
               the Representatives, except in each case for increases or
               decreases which the Prospectus discloses have occurred or may
               occur or which are described in such letter; and

               (vii) In addition to the examination referred to in their
         report(s) included or incorporated by reference in the Prospectus and
         the limited procedures, inspection of minute books, inquiries and other
         procedures referred to in paragraphs (iii) and (vi) above, they have
         carried out certain specified procedures, not constituting an
         examination in accordance with generally accepted auditing standards,
         with respect to certain amounts, percentages and financial information
         specified by the Representatives which are derived from the general
         accounting records of the Company and its subsidiaries, which appear in
         the Prospectus (excluding documents incorporated by reference) or in
         Part II of, or in exhibits and schedules to, the Registration Statement
         specified by the Representatives or in documents incorporated by
         reference in the Prospectus specified by the Representatives, and have
         compared certain of such amounts, percentages and financial information
         with the accounting records of the Company and its subsidiaries and
         have found them to be in agreement.


<PAGE>


                                   ANNEX II(a)




<PAGE>


                                   ANNEX II(b)




<PAGE>


                                   ANNEX II(c)




<PAGE>


                                   ANNEX II(d)





<PAGE>

                                                                    EXHIBIT 4.2

                            -------------------------


                              SONUS NETWORKS, INC.

                                     ISSUER

                                       TO

                           [_________________________]

                                     TRUSTEE

                            _________________________


                                    INDENTURE

                        Dated as of _____________, _____

                            -------------------------


                             SENIOR DEBT SECURITIES

                            -------------------------

<PAGE>

                                TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                                                              Page
                                                                                                              ----

<S>                                                                                                             <C>
ARTICLE I DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION................................................1

         SECTION 1.1  Definitions................................................................................1
         SECTION 1.2  Compliance Certificates And Opinions.......................................................9
         SECTION 1.3  Form of Documents Delivered to the Trustee................................................10
         SECTION 1.4  Acts of Holders ..........................................................................11
         SECTION 1.5  Notices, Etc. to the Trustee and Company..................................................13
         SECTION 1.6  Notice to Holders; Waiver.................................................................13
         SECTION 1.7  Effect of Headings and Table of Contents..................................................14
         SECTION 1.8  Successors and Assigns....................................................................14
         SECTION 1.9  Separability Clause.......................................................................14
         SECTION 1.10 Benefits of Indenture.....................................................................14
         SECTION 1.11 Governing Law.............................................................................14
         SECTION 1.12 Legal Holidays............................................................................14
         SECTION 1.13 Conflict With Trust Indenture Act.........................................................15

ARTICLE II SECURITY FORMS.......................................................................................15

         SECTION 2.1  Form Generally............................................................................15
         SECTION 2.2  Form of Security..........................................................................16
         SECTION 2.3  Form of Certificate of Authentication.....................................................27
         SECTION 2.4  Form of Conversion Notice.................................................................28
         SECTION 2.5  Form of Assignment........................................................................29

ARTICLE III THE SECURITIES......................................................................................29

         SECTION 3.1  Title and Terms...........................................................................29
         SECTION 3.2  Denominations.............................................................................30
         SECTION 3.3  Execution, Authentication, Delivery and Dating............................................30
         SECTION 3.4  Global Securities; Non-global Securities; Book-entry Provisions...........................31
         SECTION 3.5  Registration;
 Registration of Transfer and Exchange; Restrictions on
                      Transfer..................................................................................33
         SECTION 3.6  Mutilated, Destroyed, Lost or Stolen Securities...........................................34
         SECTION 3.7  Payment of Interest; Interest Rights Preserved............................................35
         SECTION 3.8  Persons Deemed Owners.....................................................................36
         SECTION 3.9  Cancellation..............................................................................36
         SECTION 3.10 Computation of Interest...................................................................37
         SECTION 3.11 CUSIP Numbers.............................................................................37

<PAGE>

ARTICLE IV SATISFACTION AND DISCHARGE...........................................................................37

         SECTION 4.1  Satisfaction and Discharge of Indenture...................................................37
         SECTION 4.2  Application of Trust Money................................................................38

ARTICLE V REMEDIES..............................................................................................39

         SECTION 5.1  Events of Default.........................................................................39
         SECTION 5.2  Acceleration of Maturity; Rescission and Annulment........................................40
         SECTION 5.3  Collection of Indebtedness and Suits for Enforcement by Trustee...........................41
         SECTION 5.4  Trustee May File Proofs of Claim..........................................................42
         SECTION 5.5  Trustee May Enforce Claims Without Possession of Securities...............................43
         SECTION 5.6  Application of Money Collected............................................................43
         SECTION 5.7  Limitation on Suits.......................................................................43
         SECTION 5.8  Unconditional Right of Holders to Receive Principal, Premium and
                      Interest and to Convert...................................................................44
         SECTION 5.9  Restoration of Rights and Remedies........................................................44
         SECTION 5.10 Rights and Remedies Cumulative............................................................45
         SECTION 5.11 Delay or Omission Not Waiver..............................................................45
         SECTION 5.12 Control by Holders .......................................................................45
         SECTION 5.13 Waiver of Past Defaults...................................................................45
         SECTION 5.14 Undertaking for Costs.....................................................................46
         SECTION 5.15 Waiver of Stay, Usury or Extension Laws...................................................46

ARTICLE VI THE TRUSTEE..........................................................................................47

         SECTION 6.1  Certain Duties and Responsibilities.......................................................47
         SECTION 6.2  Notice of Defaults........................................................................48
         SECTION 6.3  Certain Rights of Trustee.................................................................48
         SECTION 6.4  Not Responsible for Recitals or Issuance of Securities....................................49
         SECTION 6.5  May Hold Securities, Act as Trustee under Other Indentures................................49
         SECTION 6.6  Money Held in Trust.......................................................................50
         SECTION 6.7  Compensation and Reimbursement............................................................50
         SECTION 6.8  Corporate Trustee Required; Eligibility...................................................51
         SECTION 6.9  Resignation and Removal; Appointment of Successor.........................................51
         SECTION 6.10 Acceptance of Appointment by Successor....................................................52
         SECTION 6.11 Merger, Conversion, Consolidation or Succession to Business...............................53
         SECTION 6.12 Authenticating Agents.....................................................................53
         SECTION 6.13 Disqualification; Conflicting Interests...................................................54
         SECTION 6.14 Preferential Collection of Claims Against Company.........................................54


                                      -ii-

<PAGE>

ARTICLE VII CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE................................................55

         SECTION 7.1  Company May Consolidate, Etc., Only on Certain Terms......................................55
         SECTION 7.2  Successor Substituted.....................................................................55

ARTICLE VIII SUPPLEMENTAL INDENTURES............................................................................56

         SECTION 8.1  Supplemental Indentures Without Consent of Holders .......................................56
         SECTION 8.2  Supplemental Indentures with Consent of Holders ..........................................57
         SECTION 8.3  Execution of Supplemental Indentures......................................................58
         SECTION 8.4  Effect of Supplemental Indentures.........................................................58
         SECTION 8.5  Reference in Securities to Supplemental Indentures........................................58
         SECTION 8.6  Notice of Supplemental Indentures.........................................................58

ARTICLE IX MEETINGS OF HOLDERS..................................................................................59

         SECTION 9.1  Purposes for Which Meetings May Be Called.................................................59
         SECTION 9.2  Call, Notice and Place of Meetings........................................................59
         SECTION 9.3  Persons Entitled to Vote at Meetings......................................................59
         SECTION 9.4  Quorum; Action............................................................................60
         SECTION 9.5  Determination of Voting Rights; Conduct and Adjournment
                      of Meetings...............................................................................60
         SECTION 9.6  Counting Votes and Recording Action of Meetings...........................................61

ARTICLE X COVENANTS.............................................................................................62

         SECTION 10.1  Payment of Principal, Premium and Interest...............................................62
         SECTION 10.2  Maintenance of Offices or Agencies.......................................................62
         SECTION 10.3  Money for Security Payments to Be Held in Trust..........................................63
         SECTION 10.4  Existence................................................................................64
         SECTION 10.5  Payment of Taxes and Other Claims........................................................64
         SECTION 10.6  Registration and Listing.................................................................65
         SECTION 10.7  Statement by Officers as to Default......................................................65
         SECTION 10.8  Waiver of Certain Covenants..............................................................65

ARTICLE XI REDEMPTION OF SECURITIES.............................................................................66

         SECTION 11.1  Right of Redemption......................................................................66
         SECTION 11.2  Applicability of Article.................................................................66
         SECTION 11.3  Election to Redeem; Notice to Trustee....................................................66
         SECTION 11.4  Selection by Trustee of Securities to Be Redeemed........................................66
         SECTION 11.5  Notice of Redemption.....................................................................67
         SECTION 11.6  Deposit of Redemption Price..............................................................68
         SECTION 11.7  Securities Payable on Redemption Date....................................................68
         SECTION 11.8  Conversion Arrangement on Call for Redemption............................................69


                                     -iii-

<PAGE>

ARTICLE XII CONVERSION OF SECURITIES............................................................................70

         SECTION 12.1  Conversion Privilege and Conversion Rate.................................................70
         SECTION 12.2  Exercise of Conversion Privilege.........................................................70
         SECTION 12.3  Fractions of Shares......................................................................72
         SECTION 12.4  Adjustment of Conversion Rate............................................................72
         SECTION 12.5  Notice of Adjustments of Conversion Rate.................................................76
         SECTION 12.6  Notice of Certain Corporate Action.......................................................77
         SECTION 12.7  Company to Reserve Common Stock..........................................................78
         SECTION 12.8  Taxes on Conversions.....................................................................78
         SECTION 12.9  Covenant as to Common Stock..............................................................78
         SECTION 12.10 Cancellation of Converted Securities.....................................................79
         SECTION 12.11 Provision in Case of Consolidation, Merger or Sale of Assets.............................79
         SECTION 12.12 Rights Issued in respect of Common Stock.................................................80
         SECTION 12.13 Responsibility of Trustee for Conversion Provisions......................................81


ARTICLE XIII REPURCHASE OF SECURITIES AT THE OPTION OF THE HOLDER
         UPON A CHANGE IN CONTROL...............................................................................82

         SECTION 13.1  Right to Require Repurchase..............................................................82
         SECTION 13.2  Conditions to the Company's Election to Pay the Repurchase Price
                       or the Make-Whole Payment in Common Stock................................................82
         SECTION 13.3  Notices; Method of Exercising Repurchase Right, Etc......................................83
         SECTION 13.4  Certain Definitions......................................................................86
         SECTION 13.5  Consolidation, Merger, Etc...............................................................88

ARTICLE XIV HOLDERS LISTS AND REPORTS BY TRUSTEE AND COMPANY; NON-RECOURSE......................................88

         SECTION 14.1  Company to Furnish Trustee Names and Addresses of Holders................................88
         SECTION 14.2  Preservation of Information..............................................................89
         SECTION 14.3  Reports by Trustee.......................................................................89
         SECTION 14.4  Reports by Company.......................................................................89

ARTICLE XV IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS AND DIRECTORS......................................90

         SECTION 15.1  Indenture and Securities Solely Corporate Obligations....................................90
</TABLE>



                                      -iv-

<PAGE>


<TABLE>
<CAPTION>
TRUST INDENTURE ACT SECTION                                                            INDENTURE SECTION

<S>                                                                                    <C>
Section    310   (a) (1).............................................................  6.8
                 (a) (2).............................................................  6.8
                 (a) (3).............................................................  Not Applicable
                 (a) (4).............................................................  Not Applicable
                 (b).................................................................  6.8, 6.9, 6.13
Section    311   (a).................................................................  6.14
                 (b).................................................................  6.14
Section    312   (a).................................................................  14.1, 14.2(1)
                 (b).................................................................  14.2(2)
                 (c).................................................................  14.2(3)
Section    313   (a).................................................................  14.3(1)
                 (b).................................................................  14.3(1)
                 (c).................................................................  14.3(1)
                 (d).................................................................  14.3(2)
Section    314   (a)(1)..............................................................  14.4
                 (a)(2)..............................................................  14.4
                 (a)(3)..............................................................  14.4
                 (a)(4)..............................................................  10.7
                 (b).................................................................  Not Applicable
                 (c)(1)..............................................................  1.2
                 (c)(2)..............................................................  1.2
                 (c)(3)..............................................................  Not Applicable
                 (d).................................................................  Not Applicable
                 (e).................................................................  1.2
Section    315   (a).................................................................  6.1(1), 6.3
                 (b).................................................................  6.2
                 (c).................................................................  6.1(2)
                 (d).................................................................  6.1(3)
                 (e).................................................................  5.14
Section    316   (a)(last sentence).................................................   1.1 ("Outstanding")
                 (a)(1)(A)...........................................................  5.12
                 (a)(1)(B)...........................................................  5.13
                 (a)(2)..............................................................  Not Applicable
                 (b).................................................................  5.8
                 (c).................................................................  1.4
Section    317   (a)(1)..............................................................  5.3
                 (a)(2)..............................................................  5.4
                 (b).................................................................  10.3
Section    318   (a).................................................................  1.7
</TABLE>



                                      -v-

<PAGE>

         INDENTURE, dated as of _________________________,____ between SONUS
NETWORKS, INC., a corporation duly organized and existing under the laws of the
State of Delaware, having its principal office at 5 Carlisle Road, Westford,
Massachusetts 01886 (herein called the "Company"), and _____________________, a
________________ corporation, as Trustee hereunder (herein called the
"Trustee").

                             RECITALS OF THE COMPANY

         The Company has duly authorized the creation of an issue of its ____%
[Convertible](1) Notes due ______,_____ (herein called the "Securities") of
substantially the tenor and amount hereinafter set forth, and to provide
therefor the Company has duly authorized the execution and delivery of this
Indenture.

         All things necessary to make the Securities, when the Securities are
executed by the Company and authenticated and delivered hereunder, the valid
obligations of the Company, and to make this Indenture a valid agreement of the
Company, in accordance with their and its terms, have been done. [Further, all
things necessary to duly authorize the issuance of the Common Stock of the
Company issuable upon the conversion of the Securities, and to duly reserve for
issuance the number of shares of Common Stock issuable upon such conversion,
have been done.](2)

         NOW, THEREFORE, THIS INDENTURE WITNESSETH:

         For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all Holders of the Securities, as follows:

                                    ARTICLE I

             DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

         SECTION 1.1  DEFINITIONS.

         For all purposes of this Indenture, except as otherwise expressly
provided or unless the context otherwise requires:

         (1) the terms defined in this Article have the meanings assigned to
them in this Article and include the plural as well as the singular;

----------
         (1) INSERT IF SECURITIES ARE CONVERTIBLE

         (2) INSERT IF SECURITIES ARE CONVERTIBLE

<PAGE>

         (2) all accounting terms not otherwise defined herein have the meanings
assigned to them in accordance with generally accepted accounting principles in
the United States, and, except as otherwise herein expressly provided, the term
"generally accepted accounting principles" with respect to any computation
required or permitted hereunder shall mean such accounting principles as are
generally accepted at the date of such computation; and

         (3) the words "herein", "hereof" and "hereunder" and other words of
similar import refer to this Indenture as a whole and not to any particular
Article, Section or other subdivision.

         "Act", when used with respect to any Holder, has the meaning specified
in Section 1.4.

         "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For the purposes of this definition,
"control", when used with respect to any specified Person, means the power to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

         "Agent Member" means any member of, or participant in, the Depositary.

         "Applicable Procedures" means, with respect to any transfer or
transaction involving a Global Security or beneficial interest therein, the
rules and procedures of the Depositary for such Global Security, in each case to
the extent applicable to such transaction and as in effect from time to time.

         "Authenticating Agent" means any Person authorized pursuant to Section
6.12 to act on behalf of the Trustee to authenticate Securities.

         "Board of Directors" means either the board of directors of the Company
or any duly authorized committee of that board.

         "Board Resolution" means a resolution duly adopted by the Board of
Directors, a copy of which, certified by the Secretary or an Assistant Secretary
of the Company to have been duly adopted by the Board of Directors and to be in
full force and effect on the date of such certification, shall have been
delivered to the Trustee.

         "Business Day", when used with respect to any Place of Payment [or
Place of Conversion, as the case may be,](3) means each Monday, Tuesday,
Wednesday, Thursday and Friday which is not a day on which banking institutions
in such Place of Payment[, Place of Conversion](4) or other place, as the case
may be, are authorized or obligated by law or executive

----------
         (3) INSERT IF SECURITIES ARE CONVERTIBLE

         (4) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -2-

<PAGE>

order to close; provided, however, that a day on which banking institutions in
New York, New York are authorized or obligated by law or executive order to
close shall not be a Business Day for purposes of Section 13.9.

         "Change in Control" has the meaning specified in Section 14.4(2).

         "Closing Price Per Share" means, with respect to the Common Stock, for
any day, (i) the last reported bid price regular way on the Nasdaq National
Market or, (ii) if the Common Stock is not quoted on the Nasdaq National Market,
the last reported sale price regular way per share or, in case no such reported
sale takes place on such day, the average of the reported closing bid and asked
prices regular way, in either case, on the principal national securities
exchange on which the Common Stock is listed or admitted to trading, or (iii) if
the Common Stock is not quoted on the Nasdaq National Market or listed or
admitted to trading on any national securities exchange, the average of the
closing bid prices in the over-the-counter market as furnished by any New York
Stock Exchange member firm selected from time to time by the Company for that
purpose.

         "Code" has the meaning specified in Section 2.l.

         "Commission" means the United States Securities and Exchange
Commission, as from time to time constituted, created under the Exchange Act,
or, if at any time after the execution of this instrument such Commission is not
existing and performing the duties now assigned to it under the Trust Indenture
Act, then the body performing such duties at such time.

         "Common Stock" means the Common Stock, par value $0.001 per share, of
the Company authorized at the date of this instrument as originally executed.
[Subject to the provisions of Section 12.11,](5) shares issuable on
[conversion](6) or repurchase of Securities shall include only shares of Common
Stock or shares of any class or classes of common stock resulting from any
reclassification or reclassifications thereof[; provided, however, that if at
any time there shall be more than one such resulting class, the shares so
issuable on conversion of Securities shall include shares of all such classes,
and the shares of each such class then so issuable shall be substantially in the
proportion which the total number of shares of such class resulting from all
such reclassifications bears to the total number of shares of all such classes
resulting from all such reclassifications.](7)

         "common stock" includes any stock of any class of capital stock which
has no preference in respect of dividends or of amounts payable in the event of
any voluntary or involuntary


----------
         (5) INSERT IF SECURITIES ARE CONVERTIBLE

         (6) INSERT IF SECURITIES ARE CONVERTIBLE

         (7) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -3-

<PAGE>

liquidation, dissolution or winding up of the issuer thereof and which is not
subject to redemption by the issuer thereof.

         "Company" means the Person named as the "Company" in the first
paragraph of this instrument until a successor Person shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Company" shall mean such successor Person.

         "Company Notice" has the meaning specified in Section 14.3.

         "Company Request" or "Company Order" means a written request or order
signed in the name of the Company by its (i) Chairman of the Board, its Vice
Chairman of the Board, its Chief Executive Officer, its President, an Executive
Vice President or a Vice President, and by its (ii) principal financial officer,
Treasurer, an Assistant Treasurer, its Secretary or an Assistant Secretary, and
delivered to the Trustee.

         ["Conversion Agent" means any Person authorized by the Company to
convert Securities in accordance with Article XII. The Company has initially
appointed the Trustee as its Conversion Agent pursuant to Section 10.2 hereof.

         "Constituent Person" has the meaning specified in Section 12.11.](8)

         ["Conversion Price" has the meaning specified in Section 14.4(3).

         "Conversion Rate" has the meaning specified in Section 12.1.](9)

         "Corporate Trust Office" means the office of the Trustee at which at
any particular time its corporate trust business shall be principally
administered (which at the date of this Indenture is located at
______________________________, Attention: ____________________________.

         "corporation" means a corporation, company, association, joint-stock
company or business trust.

         "Defaulted Interest" has the meaning specified in Section 3.7.

         "Depositary" means, with respect to any Securities (including any
Global Securities), a clearing agency that is registered as such under the
Exchange Act and is designated by the Company to act as Depositary for such
Securities (or any successor securities clearing agency so registered).


----------
         (8) INSERT IF SECURITIES ARE CONVERTIBLE

         (9) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -4-

<PAGE>

         "Dollar" or "U.S. $" means a dollar or other equivalent unit in such
coin or currency of the United States as at the time shall be legal tender for
the payment of public and private debts.

         "DTC" means The Depository Trust Company, a New York corporation.

         "Event of Default" has the meaning specified in Section 5.1.

         "Exchange Act" means the United States Securities Exchange Act of 1934
(or any successor statute), as amended from time to time.

         "Global Security" means a Security that is registered in the Security
Register in the name of a Depositary or a nominee thereof.

         "Holder" means the Person in whose name the Security is registered in
the Security Register.

         "Indenture" means this instrument as originally executed and as it may
from time to time be supplemented or amended by one or more indentures
supplemental hereto entered into pursuant to the applicable provisions hereof,
including, for all purposes of this instrument and any such supplemental
indenture, the provisions of the Trust Indenture Act that are deemed to be a
part of and govern this instrument and any such supplemental indenture,
respectively.

         "Interest Payment Date" means the Stated Maturity of an installment of
interest on the Securities.

         "Issue Date" means ____________, ______.

         "Make-Whole Payment" has the meaning specified in Section 2.2.

         "Maturity", when used with respect to any Security, means the date on
which the principal of such Security becomes due and payable as therein or
herein provided, whether at the Stated Maturity or by declaration of
acceleration, call for redemption, exercise of the repurchase right set forth in
Article XIV or otherwise.

         ["Non-electing Share" has the meaning specified in Section 12.11.](10)

         "Notice Date" has the meaning specified in Section 2.2.

         "Notice of Default" has the meaning specified in Section 5.1.


----------
         (10) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -5-

<PAGE>

         "Officers' Certificate" means a certificate signed by (i) the Chairman
of the Board, a Vice Chairman of the Board, the Chief Executive Officer, the
President, an Executive Vice President or a Vice President and by (ii) the
principal financial officer, the Treasurer, an Assistant Treasurer, the
Secretary, or an Assistant Secretary of the Company, and delivered to the
Trustee. One of the officers signing an Officers' Certificate given pursuant to
Section 10.8 shall be the principal executive, financial or accounting officer
of the Company.

         "Opinion of Counsel" means a written opinion of counsel, who may be
counsel for the Company (including internal counsel) and who shall be reasonably
acceptable to the Trustee.

         "Outstanding", when used with respect to Securities, means, as of the
date of determination, all Securities theretofore authenticated and delivered
under this Indenture, except:

                  (i) Securities theretofore canceled by the Trustee or
         delivered to the Trustee for cancellation;

                  (ii) Securities for the payment or redemption of which money
         in the necessary amount has been theretofore deposited with the Trustee
         or any Paying Agent (other than the Company) in trust or set aside and
         segregated in trust by the Company (if the Company shall act as its own
         Paying Agent) for the Holders of such Securities; provided that, if
         such Securities are to be redeemed, notice of such redemption has been
         duly given pursuant to this Indenture or provision therefor
         satisfactory to the Trustee has been made;

                  (iii) Securities which have been paid pursuant to Section 3.6
         or in exchange for or in lieu of which other Securities have been
         authenticated and delivered pursuant to this Indenture, other than any
         such Securities in respect of which there shall have been presented to
         the Trustee proof satisfactory to it that such Securities are held by a
         bona fide purchaser in whose hands such Securities are valid
         obligations of the Company[; and

                  (iv) Securities converted into Common Stock pursuant to
         Article XII](11);

provided, however, that in determining whether the Holders of the requisite
principal amount of Outstanding Securities are present at a meeting of Holders
for quorum purposes or have given, made or taken any request, demand,
authorization, direction, notice, consent or waiver or other action hereunder as
of any date, Securities owned by the Company or any other obligor upon the
Securities or any Affiliate of the Company or such other obligor shall be
disregarded and deemed not to be Outstanding, except that, in determining
whether the Trustee shall be protected in relying upon any such determination as
to the presence of a quorum or upon any such request, demand, authorization,
direction, notice, consent, waiver or other action, only Securities which a
Responsible Officer of the Trustee has been notified in writing to be so owned
shall be so disregarded. Securities so owned which have been pledged in good
faith may be regarded as


----------
         (11) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -6-

<PAGE>

Outstanding if the pledgee is not the Company or any other obligor upon the
Securities or any Affiliate of the Company or such other obligor, and the
Trustee shall be protected in relying upon an Officers' Certificate to such
effect.

         "Over-allotment Option" has the meaning specified in Section 3.1.

         "Paying Agent" means any Person authorized by the Company to pay the
principal of or any premium or interest on any Securities on behalf of the
Company and, except as otherwise specifically set forth herein, such term shall
include the Company if it shall act as its own Paying Agent. The Company has
initially appointed the Trustee as its Paying Agent pursuant to Section 10.2
hereof.

         "Person" means any individual, corporation, limited liability company,
partnership, joint venture, trust, estate, unincorporated organization or
government or any agency or political subdivision thereof.

         ["Place of Conversion" has the meaning specified in Section 3.1.](12)

         "Place of Payment" has the meaning specified in Section 3.1.

         "Predecessor Security" of any particular Security means every previous
Security evidencing all or a portion of the same debt as that evidenced by such
particular Security; and, for the purposes of this definition, any Security
authenticated and delivered under Section 3.6 in exchange for or in lieu of a
mutilated, destroyed, lost or stolen Security shall be deemed to evidence the
same debt as the mutilated, destroyed, lost or stolen Security.

         "Record Date" means any Regular Record Date or Special Record Date.

         "Record Date Period" means the period from the close of business of any
Regular Record Date next preceding any Interest Payment Date to the opening of
business on such Interest Payment Date.

         "Redemption Date", when used with respect to any Security to be
redeemed, means the date fixed for such redemption by or pursuant to this
Indenture.

         "Redemption Price", when used with respect to any Security to be
redeemed, means the price at which it is to be redeemed pursuant to this
Indenture.

         "Regular Record Date" for interest payable in respect of any Security
on any Interest Payment Date means the ___________ or __________ (whether or not
a Business Day), as the case may be, next preceding such Interest Payment Date.


----------
         (12) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -7-

<PAGE>

         "Repurchase Date" has the meaning specified in Section 14.1.

         "Repurchase Price" has the meaning specified in Section 14.1.

         "Responsible Officer", when used with respect to the Trustee, means any
officer within the Corporate Trust Office of the Trustee, including without
limitation, any vice president, assistant vice president, assistant treasurer,
corporate trust officer or other employee of the Trustee customarily performing
functions similar to those performed by any of the above designated officers,
and also means, with respect to a particular corporate trust matter, any other
officer to whom such matter is referred because of his knowledge and familiarity
with the particular subject.

         "Securities" has the meaning ascribed to it in the first paragraph
under the caption "Recitals of the Company" and more particularly means any
Securities authenticated and delivered under this Indenture.

         "Securities Act" means the United States Securities Act of 1933 (or any
successor statute), as amended from time to time.

         "Security Register" and "Security Registrar" have the respective
meanings specified in Section 3.5.

         "Significant Subsidiary" means, with respect to any Person, a
Subsidiary of such Person that would constitute a "significant subsidiary" as
such term is defined under Rule 1-02 of Regulation S-X under the Securities Act
and the Exchange Act.

         "Special Record Date" for the payment of any Defaulted Interest means a
date fixed by the Company pursuant to Section 3.7.

         "Stated Maturity", when used with respect to any Security or any
installment of interest thereon, means the date specified in such Security as
the fixed date on which the principal of such Security or such installment of
interest is due and payable.

         "Subsidiary" means a corporation more than 50% of the outstanding
voting stock of which is owned, directly or indirectly, by the Company or by one
or more other Subsidiaries, or by the Company and one or more other
Subsidiaries. For the purposes of this definition, "voting stock" means stock or
other similar interests in the corporation which ordinarily has or have voting
power for the election of directors, or persons performing similar functions,
whether at all times or only so long as no senior class of stock or other
interests has or have such voting power by reason of any contingency.

         "Successor Security" of any particular Security means every Security
issued after, and evidencing all or a portion of the same debt as that evidenced
by, such particular Security; and,


                                      -8-

<PAGE>

for the purposes of this definition, any Security authenticated and delivered
under Section 3.6 in exchange for or in lieu of a mutilated, destroyed, lost or
stolen Security shall be deemed to evidence the same debt as the mutilated,
destroyed, lost or stolen Security.

         "Trading Day" means (i) if the Common Stock is quoted on the Nasdaq
National Market or any other system of automated dissemination of quotations of
securities prices, days on which trades may be effected through such system,
(ii) if the Common Stock is listed or admitted for trading on any national or
regional securities exchange, days on which such national or regional securities
exchange is open for business, or (iii) if the Common Stock is not listed on a
national or regional securities exchange or quoted on the Nasdaq National Market
or any other system of automated dissemination of quotation of securities
prices, days on which the Common Stock is traded regular way in the over-the-
counter market and for which a closing bid and a closing asked price for the
Common Stock are available.

         "Trust Indenture Act" means the Trust Indenture Act of 1939, and the
rules and regulations thereunder, as in force at the date as of which this
instrument was executed; provided, however, that in the event the Trust
Indenture Act of 1939 is amended after such date, "Trust Indenture Act" means,
to the extent required by any such amendment, the Trust Indenture Act of 1939,
and the rules and regulations thereunder, as so amended.

         "Trustee" means the Person named as the "Trustee" in the first
paragraph of this instrument until a successor Trustee shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Trustee" shall mean such successor Trustee.

         "Underwriting Agreement" means the Underwriting Agreement, dated as of
____________________, ______, among the Company and
_____________________________, as underwriters relating to the offering and sale
of the Securities.

         "United States" means the United States of America (including the
States and the District of Columbia), its territories, its possessions and other
areas subject to its jurisdiction (its "possessions" including Puerto Rico, the
U.S. Virgin Islands, Guam, American Samoa, Wake Island and the Northern Mariana
Islands).

         SECTION 1.2  COMPLIANCE CERTIFICATES AND OPINIONS.

         Upon any application or request by the Company to the Trustee to take
any action under any provision of this Indenture, the Company shall furnish to
the Trustee an Officers' Certificate stating that all conditions precedent, if
any, provided for in this Indenture relating to the proposed action have been
complied with and, if required by the Trust Indenture Act, an Opinion of Counsel
stating that in the opinion of such counsel all such conditions precedent, if
any, have been complied with, except that in the case of any such application or
request as to which the furnishing of such documents is specifically required by
any provision of this Indenture relating to such particular application or
request, no additional certificate or opinion need be furnished.


                                      -9-

<PAGE>

         Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this Indenture (including certificates
provided for in Section 10.7) shall include:

                  (1) a statement that each individual signing such certificate
         or opinion has read such covenant or condition and the definitions
         herein relating thereto;

                  (2) a brief statement as to the nature and scope of the
         examination or investigation upon which the statements or opinions
         contained in such certificate or opinion are based;

                  (3) a statement that, in the opinion of each such individual,
         he has made such examination or investigation as is necessary to enable
         him to express an informed opinion as to whether or not such covenant
         or condition has been complied with; and

                  (4) a statement as to whether, in the opinion of each such
         individual, such condition or covenant has been complied with.

         SECTION 1.3  FORM OF DOCUMENTS DELIVERED TO THE TRUSTEE.

         In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to such matters in one or several documents.

         Any certificate or opinion of an officer of the Company may be based,
insofar as it relates to legal matters, upon a certificate or opinion of, or
representations by, counsel, unless such officer knows, or in the exercise of
reasonable care should know, that the certificate or opinion or representations
with respect to the matters upon which such certificate or opinion is based are
erroneous. Any such certificate or opinion of counsel may be based, insofar as
it relates to factual matters, upon a certificate or opinion of, or
representations by, an officer or officers of the Company or any other Person
stating that the information with respect to such factual matters is in the
possession of the Company or such other Person, unless such counsel knows that
the certificate or opinion or representations with respect to such matters are
erroneous.

         Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Indenture, they may, but need not, be consolidated and
form one instrument.


                                      -10-

<PAGE>

         SECTION 1.4  ACTS OF HOLDERS.

         (1) Any request, demand, authorization, direction, notice, consent,
waiver or other action provided or permitted by this Indenture to be given, made
or taken by Holders may be embodied in and evidenced by (A) one or more
instruments of substantially similar tenor signed by such Holders in person or
by an agent or proxy duly appointed in writing by such Holders or (B) the record
of Holders voting in favor thereof, either in person or by proxies duly
appointed in writing, at any meeting of Holders duly called and held in
accordance with the provisions of Article IX. Such action shall become effective
when such instrument or instruments or record is delivered to the Trustee and,
where it is hereby expressly required, to the Company. The Trustee shall
promptly deliver to the Company copies of all such instruments and records
delivered to the Trustee. Such instrument or instruments and records (and the
action embodied therein and evidenced thereby) are herein sometimes referred to
as the "Act" of the Holders signing such instrument or instruments and so voting
at such meeting. Proof of execution of any such instrument or of a writing
appointing any such agent or proxy, or of the holding by any Person of a
Security, shall be sufficient for any purpose of this Indenture and (subject to
Section 6.1) conclusive in favor of the Trustee and the Company if made in the
manner provided in this Section. The record of any meeting of Holders shall be
proved in the manner provided in Section 9.6.

         (2) The fact and date of the execution by any Person of any such
instrument or writing may be proved by the affidavit of a witness of such
execution or by a certificate of a notary public or other officer authorized by
law to take acknowledgments of deeds, certifying that the individual signing
such instrument or writing acknowledged to him the execution thereof. Where such
execution is by a signer acting in a capacity other than his individual
capacity, such certificate or affidavit shall also constitute sufficient proof
of his authority.

         (3) The principal amount and serial number of any Security held by any
Person, and the date of his holding the same, shall be proved by the Security
Register.

         (4) The fact and date of execution of any such instrument or writing
and the authority of the Person executing the same may also be proved in any
other manner which the Trustee deems sufficient; and the Trustee may in any
instance require further proof with respect to any of the matters referred to in
this Section 1.4.

         (5) The Company may set any day as the record date for the purpose of
determining the Holders entitled to give or take any request, demand,
authorization, direction, notice, consent, waiver or other action, or to vote on
any action, authorized or permitted by this Indenture to be given or taken by
Holders. Promptly and in any case not later than ten days after setting a record
date, the Company shall notify the Trustee and the Holders of such record date.
If not set by the Company prior to the first solicitation of a Holder made by
any Person in respect of any such action, or, in the case of any such vote,
prior to such vote, the record date for any such action or vote shall be the
30th day (or, if later, the date of the most recent list of Holders required to
be provided pursuant to Section 15.1) prior to such first solicitation or vote,
as the case may be. With regard to any record date, the Holders on such date (or
their duly appointed agents or proxies), and only such Persons, shall be
entitled to give or take, or vote on, the relevant action,


                                      -11-

<PAGE>

whether or not such Holders remain Holders after such record date.
Notwithstanding the foregoing, the Company shall not set a record date for, and
the provisions of this paragraph shall not apply with respect to, any notice,
declaration or direction referred to in the next paragraph.

         Upon receipt by the Trustee from any Holder of (i) any notice of
default or breach referred to in Section 5.1(4) or 5.1(5), if such default or
breach has occurred and is continuing and the Trustee shall not have given such
a notice to the Company, (ii) any declaration of acceleration referred to in
Section 5.2, if an Event of Default has occurred and is continuing and the
Trustee shall not have given such a declaration to the Company, or (iii) any
direction referred to in Section 5.12, if the Trustee shall not have taken the
action specified in such direction, then, with respect to clauses (ii) and
(iii), a record date shall automatically and without any action by the Company
or the Trustee be set for determining the Holders entitled to join in such
declaration or direction, which record date shall be the close of business on
the tenth day (or, if such day is not a Business Day, the first Business Day
thereafter) following the day on which the Trustee receives such declaration or
direction, and, with respect to clause (i), the Trustee may set any day as a
record date for the purpose of determining the Holders entitled to join in such
notice of default. Promptly after such receipt by the Trustee of any such
declaration or direction referred to in clause (ii) or (iii), and promptly after
setting any record date with respect to clause (i), and as soon as practicable
thereafter, the Trustee shall notify the Company and the Holders of any such
record date so fixed. The Holders on such record date (or their duly appointed
agents or proxies), and only such Persons, shall be entitled to join in such
notice, declaration or direction, whether or not such Holders remain Holders
after such record date; provided that, unless such notice, declaration or
direction shall have become effective by virtue of Holders of the requisite
principal amount of Securities on such record date (or their duly appointed
agents or proxies) having joined therein on or prior to the 90th day after such
record date, such notice, declaration or direction shall automatically and
without any action by any Person be canceled and of no further effect. Nothing
in this paragraph shall be construed to prevent a Holder (or a duly appointed
agent or proxy thereof) from giving, before or after the expiration of such
90-day period, a notice, declaration or direction contrary to or different from,
or, after the expiration of such period, identical to, the notice, declaration
or direction to which such record date relates, in which event a new record date
in respect thereof shall be set pursuant to this paragraph. In addition, nothing
in this paragraph shall be construed to render ineffective any notice,
declaration or direction of the type referred to in this paragraph given at any
time to the Trustee and the Company by Holders (or their duly appointed agents
or proxies) of the requisite principal amount of Securities on the date such
notice, declaration or direction is so given.

         (6) Except as provided in Sections 5.12 and 5.13, any request, demand,
authorization, direction, notice, consent, election, waiver or other Act of the
Holder of any Security shall bind every future Holder of the same Security and
the Holder of every Security issued upon the registration of transfer thereof or
in exchange therefor or in lieu thereof in respect of anything done, omitted or
suffered to be done by the Trustee or the Company in reliance thereon, whether
or not notation of such action is made upon such Security.

         (7) The provisions of this Section 1.4 are subject to the provisions of
Section 9.5.


                                      -12-

<PAGE>

         SECTION 1.5  NOTICES, ETC. TO THE TRUSTEE AND THE COMPANY.

         Any request, demand, authorization, direction, notice, consent,
election, waiver or other Act of Holders or other document provided or permitted
by this Indenture to be made upon, given or furnished to, or filed with,

         (1) the Trustee by any Holder or by the Company shall be sufficient for
every purpose hereunder if made, given, furnished or filed in writing to or with
a Responsible Officer of the Trustee and received at its Corporate Trust Office,
Attention: _____________________________.

         (2) the Company by the Trustee or by any Holder shall be sufficient for
every purpose hereunder (unless otherwise herein expressly provided) if in
writing, mailed, first-class postage prepaid, or telecopied and confirmed by
mail, first-class postage prepaid, or delivered by hand or overnight courier,
addressed to the Company at 5 Carlisle Road, Westford, Massachusetts 01886,
Attention: Chief Financial Officer, or at any other address previously furnished
in writing to the Trustee by the Company.

         SECTION 1.6  NOTICE TO HOLDERS; WAIVER.

         Except as otherwise expressly provided herein, where this Indenture
provides for notice to Holders of any event, such notice shall be sufficiently
given to Holders if in writing and mailed, first-class postage prepaid or
delivered by an overnight delivery service, to each Holder affected by such
event, at the address of such Holder as it appears in the Security Register, not
earlier than the earliest date and not later than the latest date prescribed for
the giving of such notice.

         Neither the failure to mail such notice, nor any defect in any notice
so mailed, to any particular Holder shall affect the sufficiency of such notice
with respect to other Holders. In case by reason of the suspension of regular
mail service or by reason of any other cause it shall be impracticable to give
such notice by mail, then such notification to Holders as shall be made in such
manner with the approval of the Trustee, which approval shall not be
unreasonably withheld or delayed, shall constitute a sufficient notification to
such Holders for every purpose hereunder.

         Such notice shall be deemed to have been given when such notice is
received.

         Where this Indenture provides for notice in any manner, such notice may
be waived in writing by the Person entitled to receive such notice, either
before or after the event, and such waiver shall be the equivalent of such
notice. Waivers of notice by Holders shall be filed with the Trustee, but such
filing shall not be a condition precedent to the validity of any action taken in
reliance upon such waiver.


                                      -13-

<PAGE>

         SECTION 1.7  EFFECT OF HEADINGS AND TABLE OF CONTENTS.

         The Article and Section headings herein and the Table of Contents are
for convenience only and shall not affect the construction hereof.

         SECTION 1.8  SUCCESSORS AND ASSIGNS.

         All covenants and agreements in this Indenture by the Company shall
bind its successors and assigns, whether so expressed or not.

         SECTION 1.9  SEPARABILITY CLAUSE.

         In case any provision in this Indenture or the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

         SECTION 1.10  BENEFITS OF INDENTURE.

         Except as provided in the next sentence, nothing in this Indenture or
in the Securities, express or implied, shall give to any Person, other than the
parties hereto and their successors and assigns hereunder and the Holders, any
benefit or legal or equitable right, remedy or claim under this Indenture.

         SECTION 1.11  GOVERNING LAW.

         THIS INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, THE UNITED STATES OF AMERICA,
WITHOUT REGARD TO THE CONFLICTS OF LAWS PRINCIPLES THEREOF.

         SECTION 1.12 LEGAL HOLIDAYS.

         In any case where any Interest Payment Date, Redemption Date,
Repurchase Date or Stated Maturity of any Security [or the last day on which a
Holder has a right to convert his Security(13)] shall not be a Business Day at a
Place of Payment [or Place of Conversion, as the case may be](14), then
(notwithstanding any other provision of this Indenture or of the Securities)
payment of principal of, premium, if any, or interest on, or the payment of the
Redemption Price or Repurchase Price (whether the same is payable in cash or in
shares of Common Stock) with respect to[, or delivery for conversion of,](15)
such Security need not be made at such Place of


----------
         (13) INSERT IF SECURITIES ARE CONVERTIBLE

         (14) INSERT IF SECURITIES ARE CONVERTIBLE

         (15) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -14-

<PAGE>

Payment [or Place of Conversion, as the case may be,](16) on or by such day, but
may be made on or by the next succeeding Business Day at such Place of Payment
[or Place of Conversion, as the case may be,](17) with the same force and effect
as if made on the Interest Payment Date, Redemption Date or Repurchase Date, or
at the Stated Maturity [or by such last day for conversion](18); provided,
however, that in the case that payment is made on such succeeding Business Day,
no interest shall accrue on the amount so payable for the period from and after
such Interest Payment Date, Redemption Date, Repurchase Date, Stated Maturity
[or last day for conversion](19), as the case may be.

         SECTION 1.13  CONFLICT WITH TRUST INDENTURE ACT.

         If any provision hereof limits, qualifies or conflicts with a provision
of the Trust Indenture Act that is required under the Trust Indenture Act to be
a part of and govern this Indenture, the latter provision shall control. If any
provision of this Indenture modifies or excludes any provision of the Trust
Indenture Act that may be so modified or excluded, the latter provision shall be
deemed to apply to this Indenture as so modified or to be excluded, as the case
may be. Until such time as this Indenture shall be qualified under the Trust
Indenture Act, this Indenture, the Company and the Trustee shall be deemed for
all purposes hereof to be subject to and governed by the Trust Indenture Act to
the same extent as would be the case if this Indenture were so qualified on the
date hereof.

                                   ARTICLE II

                                 SECURITY FORMS

         SECTION 2.1  FORM GENERALLY.

         The Securities shall be in substantially the form set forth in this
Article, with such appropriate insertions, omissions, substitutions and other
variations as are required or permitted by this Indenture, and may have such
letters, numbers or other marks of identification and such legends or
endorsements placed thereon as may be required to comply with the rules of any
securities exchange, the Internal Revenue Code of 1986, as amended, and
regulations thereunder (the "Code"), or as may, consistent herewith, be
determined by the officers executing such Securities, as evidenced by their
execution thereof. All Securities shall be issued in registered form, as opposed
to bearer form.


----------
         (16) INSERT IF SECURITIES ARE CONVERTIBLE

         (17) INSERT IF SECURITIES ARE CONVERTIBLE

         (18) INSERT IF SECURITIES ARE CONVERTIBLE

         (19) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -15-

<PAGE>

         The Trustee's certificates of authentication shall be in substantially
the form set forth in Section 2.3.

         [Conversion notices shall be in substantially the form set forth in
Section 2.4.](20)

         Repurchase notices shall be substantially in the form set forth in
Section 2.2.

         The Securities shall be printed, lithographed, typewritten or engraved
or produced by any combination of these methods or may be produced in any other
manner permitted by the rules of any automated quotation system or securities
exchange (including on steel engraved borders if so required by any securities
exchange upon which the Securities may be listed) on which the Securities may be
quoted or listed, as the case may be or, if the Securities are not listed on a
securities exchange or automated quotation system, in any other manner approved
by the Company, all as determined by the officers executing such Securities, as
evidenced by their execution thereof.

         Upon their original issuance, Securities shall be issued in the form of
one or more Global Securities without interest coupons and shall be registered
in the name of DTC, as Depositary, or its nominee and deposited with the
Trustee, as custodian for DTC, for credit by DTC to the respective accounts of
beneficial owners of the Securities represented thereby (or such other accounts
as they may direct).

         SECTION 2.2  FORM OF SECURITY.

[FORM OF FACE]

         [THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY:

         THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF THE DEPOSITARY OR A
NOMINEE OF THE DEPOSITARY, WHICH MAY BE TREATED BY THE COMPANY, THE TRUSTEE AND
ANY AGENT THEREOF AS OWNER AND HOLDER OF THIS SECURITY FOR ALL PURPOSES.

         THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY
FOR WHICH THE DEPOSITORY TRUST COMPANY IS TO BE THE DEPOSITARY:

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY, A NEW YORK


----------
         (20) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -16-

<PAGE>

CORPORATION ("DTC"), TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER,
EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF
CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE
OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER
USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS
THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

         UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN
DEFINITIVE REGISTERED FORM IN THE LIMITED CIRCUMSTANCES REFERRED TO IN THE
INDENTURE, THIS GLOBAL SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE
DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO
THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY
SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR
DEPOSITARY.]

                           SONUS NETWORKS, INC.

______% [CONVERTIBLE](21) NOTE DUE _________________, ____

No.____  $                          
          __________________________

CUSIP NO. ___________

         SONUS NETWORKS, INC., a corporation duly organized and existing 
under the laws of the State of Delaware (herein called the "Company", which 
term includes any successor Person under the Indenture referred to on the 
reverse hereof), for value received, hereby promises to pay to 
_________________, or registered assigns, the principal sum of ________ 
United States Dollars (U.S. $______ ) (which principal amount may from time 
to time be increased or decreased to such other principal amounts (which, 
taken together with the principal amounts of all other Outstanding 
Securities, shall not exceed $___________ (or $___________ if the 
Over-allotment Option is exercised in full)) by adjustments made on the 
records of the Trustee hereinafter referred to in accordance with the 
Indenture) on __________________, ______ and to pay interest thereon, from 
_________, _____, or from the most recent Interest Payment Date (as defined 
below) to which interest has been paid or duly provided for, semi-annually in 
arrears on __________________ and __________________ in each year (each, an 
"Interest Payment Date"), commencing _______, _____, at the rate of _____% 
per annum, until the principal hereof is due, and at the rate of _____% per 
annum on any overdue principal and premium, if

----------
         (21) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -17-

<PAGE>

any, and, to the extent permitted by law, on any overdue interest. The interest
so payable, and punctually paid or duly provided for, on any Interest Payment
Date will, as provided in the Indenture, be paid to the Person in whose name
this Security (or one or more Predecessor Securities) is registered at the close
of business on the Regular Record Date for such interest, which shall be the
_________ or _________ (whether or not a Business Day), as the case may be, next
preceding such Interest Payment Date. Except as otherwise provided in the
Indenture, any such interest not so punctually paid or duly provided for will
forthwith cease to be payable to the Holder on such Regular Record Date and may
either be paid to the Person in whose name this Security (or one or more
Predecessor Securities) is registered at the close of business on a Special
Record Date for the payment of such Defaulted Interest to be fixed by the
Company, notice whereof shall be given to Holders not less than 10 days prior to
such Special Record Date, or be paid at any time in any other lawful manner not
inconsistent with the requirements of any automated quotation system or
securities exchange on which the Securities may be quoted or listed, and upon
such notice as may be required by such exchange, all as more fully provided in
the Indenture. Payments of principal shall be made upon the surrender of this
Security at the option of the Holder at the Corporate Trust Office of the
Trustee, or at such other office or agency of the Company as may be designated
by it for such purpose in the Borough of Manhattan, The City of New York, in
such lawful monies of the United States of America as at the time of payment
shall be legal tender for the payment of public and private debts, or at such
other offices or agencies as the Company may designate, by United States Dollar
check drawn on, or wire transfer to, a United States Dollar account (such a wire
transfer to be made only to a Holder of an aggregate principal amount of
Securities in excess of U.S. $2,000,000 and only if such Holder shall have
furnished wire instructions in writing to the Trustee no later than 15 days
prior to the relevant payment date) maintained by the payee with a bank in the
Borough of Manhattan, The City of New York. Payment of interest on this Security
may be made by United States Dollar check mailed to the address of the Person
entitled thereto as such address shall appear in the Security Register, or, upon
written application by the Holder to the Security Registrar setting forth wire
instructions not later than the relevant Record Date, by wire transfer to a
United States Dollar account (such a wire transfer to be made only to a Holder
of an aggregate principal amount of Securities in excess of U.S. $2,000,000 and
only if such Holder shall have furnished wire instructions in writing to the
Trustee no later than 15 days prior to the relevant payment date) maintained by
the payee with a bank in the Borough of Manhattan, The City of New York. Except
as specifically provided herein and in the Indenture, the Company shall not be
required to make any payment with respect to any tax, assessment or other
governmental charge imposed by any government or any political subdivision or
taxing authority thereof or therein.

         Interest on the Securities shall be computed on the basis of a 
360-day year of twelve 30-day months.

         Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

         Unless the certificate of authentication hereon has been executed by
the Trustee referred to on the reverse hereof or an Authenticating Agent by the
manual signature of one of their


                                      -18-

<PAGE>

respective authorized signatories, this Security shall not be entitled to any
benefit under the Indenture or be valid or obligatory for any purpose.

         IN WITNESS WHEREOF, the Company has caused this Security to be duly
executed.

                                       SONUS NETWORKS, INC.

                                       By:_____________________________________
                                       Name:
                                       Title:

Attest:

By:_________________________________
Name:
Title:

TRUSTEE'S CERTIFICATE OF AUTHENTICATION

This is one of the Securities referred to in the within-mentioned Indenture.

     Dated:______________________________
     as Trustee

     By:_________________________________
        Authorized Signatory


                                [FORM OF REVERSE]

This Security is one of a duly authorized issue of securities of the Company
designated as its "_____% [CONVERTIBLE](22) Notes due __________________"
(herein called the "Securities"), limited in aggregate principal amount to U.S.
$___________ (or $___________ if the Over-allotment Option is exercised in
full), issued and to be issued under an Indenture, dated as of _______________,
_____ (herein called the "Indenture"), between the Company and
_________________, as Trustee (herein called the "Trustee", which term includes
any successor trustee under the Indenture), and to which Indenture and all
indentures supplemental thereto reference is hereby made for a statement of the
respective rights, limitations of rights, duties and immunities thereunder of
the Company, the Trustee and the Holders of the Securities and of the terms upon
which the Securities are, and are to be, authenticated and delivered. As
provided in the Indenture and subject to certain limitations therein set forth,
Securities are exchangeable for


----------
         (22) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -19-

<PAGE>

a like aggregate principal amount of Securities of any authorized denominations
as requested by the Holder surrendering the same upon surrender of the Security
or Securities to be exchanged, at the Corporate Trust Office of the Trustee. The
Trustee upon such surrender by the Holder will issue the new Securities in the
requested denominations. No sinking fund is provided for the Securities. The
Securities are subject to redemption by the Company, in whole or in part, at any
time prior to __________________, ________, upon notice as set forth in Section
11.5 of the Indenture, at a redemption price equal to the principal amount of
the Securities to be redeemed plus accrued and unpaid interest, if any, to the
Redemption Date if the Closing Price of the Common Stock shall have
________________ for at least 20 Trading Days in any 30-Trading Day period
ending on the Trading Day prior to the date of mailing of the notice of
redemption pursuant to Section 11.5 of the Indenture (the "Notice Date"). Upon
any such redemption, the Company shall make an additional payment (the
"Make-Whole Payment") with respect to the Securities called for redemption to
holders on the Notice Date in an amount equal to $_______ per U.S.$1,000
Security, less the amount of any interest actually paid on such Security prior
to the Notice Date. The Company shall make the Make-Whole Payment on all
Securities called for redemption[,including any Securities converted into Common
Stock pursuant to the terms of the Indenture after the Notice Date and prior to
the Redemption Date.](23) The Company may make the Make-Whole Payment, at its
option, in cash, in shares of Common Stock or through a combination of cash and
shares of Common Stock. For purposes of this paragraph, the fair market value of
shares of Common Stock shall be determined by the Company and shall be equal to
___% of the average of the Closing Price Per Share for the five consecutive
Trading Days immediately preceding the Redemption Date.

         The Securities are also subject to redemption at the option of the
Company at any time on or after __________________,___ in whole or in part, upon
not less than 30 nor more than 60 days notice to the Holders prior to the
Redemption Date at the Redemption Prices (expressed as percentages of the
principal amount) set forth below.

         The following table sets forth the Redemption Prices (expressed as
percentages of the principal amount) if such Security is redeemed during the
12-month period beginning on __________ of the following years:

YEAR                                REDEMPTION PRICE




and thereafter at a Redemption Price equal to _____% of the principal amount,
together, in each case, with accrued interest to the Redemption Date; provided,
however, that interest installments on Securities whose Stated Maturity is on or
prior to such Redemption Date will be payable to the Holders of such Securities,
or one or more Predecessor Securities, of record at the close of


----------
         (23) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -20-

<PAGE>

business on the relevant Record Dates referred to on the face hereof, all as
provided in the Indenture.

         In the event of a redemption of the Securities, the Company will not be
required (a) to register the transfer or exchange of Securities for a period of
15 days immediately preceding the date notice is given identifying the serial
numbers of the Securities called for such redemption or (b) to register the
transfer or exchange of any Security, or portion thereof, called for redemption.
In any case where the due date for the payment of the principal of, premium, if
any, or interest on any Security [or the last day on which a Holder has a right
to convert his Security](24) shall be, at any Place of Payment [or Place of
Conversion, as the case may be,](25) a day on which banking institutions at such
Place of Payment [or Place of Conversion](26) are authorized or obligated by law
or executive order to close, then payment of principal, premium, if any, or
interest, [or delivery for conversion of such Security](27) need not be made on
or by such date at such place but may be made on or by the next succeeding day
at such place which is not a day on which banking institutions are authorized or
obligated by law or executive order to close, with the same force and effect as
if made on the date for such payment or the date fixed for redemption or
repurchase[, or by such last day for conversion,](28) and no interest shall
accrue on the amount so payable for the period from and after such due date.

         [Subject to and upon compliance with the provisions of the Indenture,
the Holder of this Security is entitled, at his option, at any time on or before
the close of business on the date of Maturity, or in case this Security or a
portion hereof is called for redemption or the Holder hereof has exercised his
right to require the Company to repurchase this Security or such portion hereof,
then in respect of this Security until and including, but (unless the Company
defaults in making the payment due upon redemption or repurchase, as the case
may be) not after, the close of business on the Business Day immediately
preceding the Redemption Date or the Repurchase Date, as the case may be, to
convert this Security (or any portion of the principal amount hereof that is an
integral multiple of U.S. $1,000, provided that the unconverted portion of such
principal amount is an integral multiple of U.S. $1,000) into fully paid and
nonassessable shares of Common Stock of the Company at an initial Conversion
Rate of ______ shares of Common Stock for each U.S. $1,000 principal amount of
Securities (or at the current adjusted Conversion Rate if an adjustment has been
made as provided in the Indenture) by surrender of this Security, duly endorsed
or assigned to the Company or in blank and, in case such surrender shall be made
during the period from the close of business on any Regular Record Date next
preceding any


----------
         (24) INSERT IF SECURITIES ARE CONVERTIBLE

         (25) INSERT IF SECURITIES ARE CONVERTIBLE

         (26) INSERT IF SECURITIES ARE CONVERTIBLE

         (27) INSERT IF SECURITIES ARE CONVERTIBLE

         (28) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -21-

<PAGE>

Interest Payment Date to the opening of business on such Interest Payment Date
(except if this Security or portion thereof has been called for redemption on a
Redemption Date or is repurchasable on a Repurchase Date occurring, in either
case, during such period and, as a result, the right to convert would terminate
in such period), also accompanied by payment in New York Clearing House or other
funds acceptable to the Company of an amount equal to the interest payable on
such Interest Payment Date on the principal amount of this Security then being
converted, and also the conversion notice hereon duly executed, to the Company
at the Corporate Trust Office of the Trustee, or at such other office or agency
of the Company, subject to any laws or regulations applicable thereto and
subject to the right of the Company to terminate the appointment of any
Conversion Agent (as defined below) as may be designated by it for such purpose
in the Borough of Manhattan, The City of New York, or at such other offices or
agencies as the Company may designate in the Borough of Manhattan, The City of
New York (each a "Conversion Agent"), provided, further, that if this Security
or portion hereof has been called for redemption on a Redemption Date or is
repurchasable on a Repurchase Date occurring, in either case, during the period
from the close of business on any Regular Record Date next preceding any
Interest Payment Date to the opening of business on such succeeding Interest
Payment Date, and is surrendered for conversion during such period, then the
Holder of this Security on such Regular Record Date will be entitled to receive
the interest accruing hereon from the Interest Payment Date next preceding the
date of such conversion to such succeeding Interest Payment Date and the Holder
of this Security who converts this Security or a portion hereof during such
period shall not be required to pay such interest upon surrender of this
Security for conversion. Subject to the provisions of the preceding sentence
and, in the case of a conversion after the close of business on the Regular
Record Date next preceding any Interest Payment Date and on or before the close
of business on such Interest Payment Date, to the right of the Holder of this
Security (or any Predecessor Security of record as of such Regular Record Date)
to receive the related installment of interest to the extent and under the
circumstances provided in the Indenture, no cash payment or adjustment is to be
made on conversion for interest accrued hereon from the Interest Payment Date
next preceding the day of conversion, or for dividends on the Common Stock
issued on conversion hereof. The Company shall thereafter deliver to the Holder
the fixed number of shares of Common Stock (together with any cash adjustment,
as provided in the Indenture) into which this Security is convertible and such
delivery will be deemed to satisfy the Company's obligation to pay the principal
amount of this Security. No fractions of shares or scrip representing fractions
of shares will be issued on conversion, but instead of any fractional interest
(calculated to the nearest 1/100th of a share) the Company shall pay a cash
adjustment as provided in the Indenture. The Conversion Rate is subject to
adjustment as provided in the Indenture. In addition, the Indenture provides
that in case of certain consolidations or mergers to which the Company is a
party (other than a consolidation or merger that does not result in any
reclassification, conversion, exchange or cancellation of the Common Stock) or
the conveyance, transfer, sale or lease of all or substantially all of the
property and assets of the Company, the Indenture shall be amended, without the
consent of any Holders, so that this Security, if then Outstanding, will be
convertible thereafter, during the period this Security shall be convertible as
specified above, only into the kind and amount of securities, cash and other
property receivable upon such consolidation, merger, conveyance, transfer, sale
or lease by a holder of the number of shares of Common Stock of the Company into
which this


                                      -22-

<PAGE>

Security could have been converted immediately prior to such consolidation,
merger, conveyance, transfer, sale or lease (assuming such holder of Common
Stock is not a Constituent Person, failed to exercise any rights of election and
received per share the kind and amount received per share by a plurality of
Non-electing Shares). No adjustment in the Conversion Rate will be made until
such adjustment would require an increase or decrease of at least one percent of
such rate, provided that any adjustment that would otherwise be made will be
carried forward and taken into account in the computation of any subsequent
adjustment.](29) If a Change in Control occurs, the Holder of this Security, at
the Holder's option, shall have the right, in accordance with the provisions of
the Indenture, to require the Company to repurchase this Security (or any
portion of the principal amount hereof that is equal to an integral multiple of
$1,000, provided that the portion of the principal amount of this Security to be
Outstanding after such repurchase is an integral multiple of U.S. $1,000) for
cash at a Repurchase Price equal to ____% of the principal amount thereof plus
interest accrued to the Repurchase Date. At the option of the Company as
determined prior to the time of the Change in Control, the Repurchase Price may
be paid in cash or, subject to the conditions provided in the Indenture, by
delivery of shares of Common Stock having a fair market value equal to the
Repurchase Price. For purposes of this paragraph, the fair market value of
shares of Common Stock shall be determined by the Company and shall be equal to
_______% of the average of the Closing Price Per Share for the five consecutive
Trading Days immediately preceding and including the third Trading Day prior to
the Repurchase Date. Whenever in this Security there is a reference, in any
context, to the principal of any Security as of any time, such reference shall
be deemed to include reference to the Repurchase Price payable in respect of
such Security to the extent that such Repurchase Price is, was or would be so
payable at such time, and express mention of the Repurchase Price in any
provision of this Security shall not be construed as excluding the Repurchase
Price so payable in those provisions of this Security when such express mention
is not made; provided, however, that, for the purposes of the second succeeding
paragraph, such reference shall be deemed to include reference to the Repurchase
Price only to the extent the Repurchase Price is payable in cash.

         The following paragraph shall appear in each Global Security:

         [In the event of a deposit or withdrawal of an interest in this
Security, including an exchange, transfer, redemption, repurchase [or
conversion](30) of this Security in part only, the Trustee, as custodian of the
Depositary, shall make an adjustment on its records to reflect such deposit or
withdrawal in accordance with the Applicable Procedures.]

         [The following paragraph shall appear in each Security that is not a
Global Security:


----------
         (29) INSERT IF SECURITIES ARE CONVERTIBLE

         (30) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -23-

<PAGE>

         In the event of redemption, repurchase [or conversion](31) of this
Security in part only, a new Security or Securities for the unredeemed,
unrepurchased [or unconverted](32) portion hereof will be issued in the name of
the Holder hereof.]

         If an Event of Default shall occur and be continuing, the principal of
all the Securities, together with accrued interest to the date of declaration,
may be declared due and payable in the manner and with the effect provided in
the Indenture. Upon payment (i) of the amount of principal so declared due and
payable, together with accrued interest to the date of declaration, and (ii) of
interest on any overdue principal and, to the extent permitted by applicable
law, overdue interest, all of the Company's obligations in respect of the
payment of the principal of and interest on the Securities shall terminate.

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities under the Indenture at
any time by the Company and the Trustee with either (a) the written consent of
the Holders of not less than ___________ in principal amount of the Securities
at the time Outstanding, or (b) by the adoption of a resolution, at a meeting of
Holders of the Outstanding Securities at which a quorum is present, by the
Holders of at least _______% in aggregate principal amount of the Outstanding
Securities represented and entitled to vote at such meeting. The Indenture also
contains provisions permitting the Holders of specified percentages in principal
amount of the Securities at the time Outstanding, on behalf of the Holders of
all the Securities, to waive compliance by the Company with certain provisions
of the Indenture and certain past defaults under the Indenture and their
consequences. Any such consent or waiver by the Holder of this Security shall be
conclusive and binding upon such Holder and upon all future Holders of this
Security and of any Security issued in exchange therefor or in lieu hereof
whether or not notation of such consent or waiver is made upon this Security or
such other Security as provided in and subject to the provisions of the
Indenture, the Holder of this Security shall not have the right to institute any
proceeding with respect to the Indenture or for the appointment of a receiver or
trustee or for any other remedy thereunder, unless such Holder shall have
previously given the Trustee written notice of a continuing Event of Default,
the Holders of not less than 25% in principal amount of the Outstanding
Securities shall have made written request to the Trustee to institute
proceedings in respect of such Event of Default as Trustee and offered the
Trustee reasonable indemnity and the Trustee shall not have received from the
Holders of a majority in principal amount of the Securities Outstanding a
direction inconsistent with such request, and shall have failed to institute any
such proceeding, for 60 days after receipt of such notice, request and offer of
indemnity. The foregoing shall not apply to any suit instituted by the Holder of
this Security for the enforcement of any payment of principal hereof, premium,
if any, or interest hereon on or after the respective due dates


----------
         (31) INSERT IF SECURITIES ARE CONVERTIBLE

         (32) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -24-

<PAGE>

expressed herein [or for the enforcement of the right to convert this Security
as provided in the Indenture.](33)

         No reference herein to the Indenture and no provision of this Security
or of the Indenture shall alter or impair the obligation of the Company, which
is absolute and unconditional, to pay the principal of, premium, if any, and
interest on this Security at the times, places and rate, and in the coin or
currency, herein prescribed [or to convert this Security as provided in the
Indenture.](34)

         As provided in the Indenture and subject to certain limitations therein
set forth, the transfer of this Security is registrable in the Security Register
upon surrender of this Security for registration of transfer at the Corporate
Trust Office of the Trustee or at such other office or agency of the Company as
may be designated by it for such purpose in the Borough of Manhattan, The City
of New York (which shall initially be an office or agency of the Trustee), or at
such other offices or agencies as the Company may designate, duly endorsed by,
or accompanied by a written instrument of transfer in form satisfactory to the
Company and the Security Registrar duly executed by, the Holder thereof or his
attorney duly authorized in writing, and thereupon one or more new Securities,
of authorized denominations and for the same aggregate principal amount, will be
issued to the designated transferee or transferees by the Registrar. No service
charge shall be made for any such registration of transfer or exchange, but the
Company may require payment of a sum sufficient to recover any tax or other
governmental charge payable in connection therewith.

         Prior to due presentation of this Security for registration of
transfer, the Company, the Trustee, any Authenticating Agent or any other agent
of the Company or the Trustee may treat the Person in whose name this Security
is registered as the owner hereof for all purposes, whether or not this Security
be overdue, and neither the Company, the Trustee nor any Authenticating Agent or
other agent of the Company or the Trustee shall be affected by notice to the
contrary.

         No recourse for the payment of the principal (and premium, if any or
interest on this Security and no recourse under or upon any obligation, covenant
or agreement of the Company in the Indenture or any indenture supplemental
thereto or in any Security, or because of the creation of any indebtedness
represented thereby, shall be had against any incorporator, stockholder,
employee, agent, officer or director or subsidiary, as such, past, present or
future, of the Company or of any successor corporation, either directly or
through the Company or any successor corporation, whether by virtue of any
constitution, statute or rule of law or by the enforcement of any assessment or
penalty or otherwise, all such liability being, by the acceptance hereof and as
part of consideration for the issue hereof, expressly waived and released.


----------
         (33) INSERT IF SECURITIES ARE CONVERTIBLE

         (34) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -25-

<PAGE>

         THE INDENTURE AND THIS SECURITY SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, UNITED STATES OF AMERICA,
WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF LAWS.

         All terms used in this Security which are defined in the Indenture
shall have the meanings assigned to them in the Indenture.

                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription of the face
of this Security, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM       as tenants in common
TEN ENT       as tenants by the entireties
JT TEN        as joint tenants with right of survivorship and not as tenants in
              common

UNIF GIFT MIN ACT ____ Custodian ____
                 (Cust)          (Minor)
                 under Uniform Gifts
                 to Minors Act_____

         Additional abbreviations may also be used though not in the above list.

         ELECTION OF HOLDER TO REQUIRE REPURCHASE

         (1) Pursuant to Section 14.1 of the Indenture, the undersigned hereby
elects to have this Security repurchased by the Company.

         (2) The undersigned hereby directs the Trustee or the Company to pay it
or ______________ an amount in cash or, at the Company's election, Common Stock
valued as set forth in the Indenture, equal to ______% of the principal amount
to be repurchased (as set forth below), plus interest accrued to the Repurchase
Date, as provided in the Indenture.

Dated:

_________________________

_________________________
Signature(s)


                                      -26-

<PAGE>

Signature(s) must be guaranteed by an Eligible Guarantor Institution with
membership in an approved signature guarantee program pursuant to Rule 17Ad-15
under the Securities Exchange Act of 1934.

_________________________
Signature Guaranteed

Principal amount to be repurchased (an integral multiple of $1,000):

___________________


Remaining principal amount, if any, following such repurchase (not less than
U.S. $1,000): ______________

NOTICE: The signature to the foregoing Election must correspond to the Name as
written upon the face of this Security in every particular, without alteration
or any change whatsoever.

SECTION 2.3 FORM OF CERTIFICATE OF AUTHENTICATION.

         The Trustee's certificates of authentication shall be in substantially
the following form:

         This is one of the Securities referred to in the within-mentioned
Indenture.

Dated:[DATE OF AUTHENTICATION]


___________________________________

         _____________________________,
         as Trustee

         By:___________________________
         Authorized Signatory


                                      -27-

<PAGE>

         [SECTION 2.4  FORM OF CONVERSION NOTICE.

                                CONVERSION NOTICE

         The undersigned Holder of this Security hereby irrevocably exercises 
the option to convert this Security, or any portion of the principal amount 
hereof (which is an integral multiple of U.S. $1,000 provided that the 
unconverted portion of such principal amount is an integral multiple of U.S. 
$1,000) below designated, into shares of Common Stock in accordance with the 
terms of the Indenture referred to in this Security, and directs that such 
shares, together with a check in payment for any fractional share and any 
Securities representing any unconverted principal amount hereof, be delivered 
to and be registered in the name of the undersigned unless a different name 
has been indicated below. If shares of Common Stock or Securities are to be 
registered in the name of a Person other than the undersigned, (a) the 
undersigned will pay all transfer taxes payable with respect thereto and (b) 
signature(s) must be guaranteed by an Eligible Guarantor Institution with 
membership in an approved signature guarantee program pursuant to Rule 
17Ad-15 under the Securities Exchange Act of 1934. Any amount required to be 
paid by the undersigned on account of interest accompanies this Security.

Dated:__________________ ________________________
                         Signature(s)

If shares or Securities are to be registered in the name of a Person other than
the Holder, please print such Person's name and address:

_______________________
(Name)


_______________________

_______________________
(Address)

Social Security or other Identification
Number, if any

_______________________
[Signature Guaranteed]

If only a portion of the Securities is to be converted, please indicate:

1.  Principal amount to be converted: U.S. $ ___________


                                      -28-

<PAGE>

2.  Principal amount and denomination of Securities representing unconverted
principal amount to be issued:

         Amount: U.S. $___________Denominations: U.S. $____________

(any integral multiple of U.S. $1,000, provided that the unconverted portion of
such principal amount is an integral multiple of U.S. $1,000)](35)

         SECTION 2.5  FORM OF ASSIGNMENT.

         For value received ________________ hereby sell(s), assign(s) and
transfer(s) unto ________________ (Please insert social security or other
identifying number of assignee) the within Security, and hereby irrevocably
constitutes and appoints ____________________as attorney to transfer the said
Security on the books of the Company, with full power of substitution in the
premises.

Dated:___________________ _____________________
         Signature(s)

Signature(s) must be guaranteed by an Eligible Guarantor Institution with
membership in an approved signature guarantee program pursuant to Rule 17Ad-15
under the Securities Exchange Act of 1934.

_______________________
Signature Guaranteed

                                   ARTICLE III

                                 THE SECURITIES

         SECTION 3.1  TITLE AND TERMS.

         The aggregate principal amount of Securities which may be authenticated
and delivered under this Indenture is limited to U.S. $____________ (or
$_____________ if the Over-allotment Option set forth in the Underwriting
Agreement is exercised in full (the "Over-allotment Option")), except for
Securities authenticated and delivered pursuant to Section 3.4, 3.5, 3.6, 8.5,
11.7[, 12.2](36) or 14.3(5) in exchange for, or in lieu of, other Securities
previously authenticated and delivered under this Indenture.


----------
         (35) INSERT IF SECURITIES ARE CONVERTIBLE

         (36) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -29-

<PAGE>

         The Securities shall be known and designated as the "____%
[Convertible](37) Notes due _________, ______" of the Company. Their Stated
Maturity shall be _______________, _____ and they shall bear interest on their
principal amount from ____________, _____, payable semi-annually in arrears on
________ and ________ in each year, commencing _________________, ______, at the
rate of ____% per annum until the principal thereof is due and at the rate of
____% per annum on any overdue principal and, to the extent permitted by law, on
any overdue interest; provided, however, that payments shall only be made on
Business Days as provided in Section 1.12.

         The principal of, premium, if any, and interest on the Securities shall
be payable as provided in the form of Securities set forth in Section 2.2, and
the Repurchase Price, whether payable in cash or in shares of Common Stock,
shall be payable at such places as are identified in the Company Notice given
pursuant to Section 14.3 (any city in which any Paying Agent is located being
herein called a "Place of Payment").

         The Securities shall be redeemable at the option of the Company at any
time on or after _________________, ____, in whole or in part, subject to the
conditions and as otherwise provided in Article XI and in the form of Securities
set forth in Section 2.2.

         The Securities are not entitled to the benefit of any sinking fund.

         [The Securities shall be convertible as provided in Article XII (any
city in which any Conversion Agent is located being herein called a "Place of
Conversion").](38)

         The Securities shall be subject to repurchase by the Company at the
option of the Holders as provided in Article XIV.

         SECTION 3.2  DENOMINATIONS.

         The Securities shall be issuable only in registered form, without
coupons, in denominations of U.S. $1,000 and integral multiples thereof.

         SECTION 3.3  EXECUTION, AUTHENTICATION, DELIVERY AND DATING.

         The Securities shall be executed on behalf of the Company by its
Chairman of the Board, its Vice Chairman of the Board, its Chief Executive
Officer, its President, or one of its Vice Presidents, with or without a
corporate seal reproduced thereon, and attested by its Chief Executive Officer,
President, Chief Financial Officer, Secretary or one of its Assistant
Secretaries. Any such signature may be manual or facsimile.


----------
         (37) INSERT IF SECURITIES ARE CONVERTIBLE

         (38) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -30-

<PAGE>

         Securities bearing the manual or facsimile signature of individuals who
were at any time the proper officers of the Company shall bind the Company,
notwithstanding that such individuals or any of them have ceased to hold such
offices prior to the authentication and delivery of such Securities or did not
hold such offices at the date of such Securities.

         At any time and from time to time after the execution and delivery of
this Indenture, the Company may deliver Securities executed by the Company to
the Trustee or to its order for authentication, together with a Company Order
for the authentication and delivery of such Securities, and the Trustee in
accordance with such Company Order shall authenticate and make available for
delivery such Securities as in this Indenture provided and not otherwise.

         Each Security shall be dated the date of its authentication.

         No Security shall be entitled to any benefit under this Indenture or be
valid or obligatory for any purpose unless there appears on such Security a
certificate of authentication substantially in the form provided for herein
executed by the Trustee by manual signature of an authorized signatory, and such
certificate upon any Security shall be conclusive evidence, and the only
evidence, that such Security has been duly authenticated and delivered
hereunder.

         SECTION 3.4  GLOBAL SECURITIES; NON-GLOBAL SECURITIES; BOOK-ENTRY
PROVISIONS.

         (1)      Global Securities

                  (i) Each Global Security authenticated under this Indenture
         shall be registered in the name of the Depositary designated by the
         Company for such Global Security or a nominee thereof and delivered to
         such Depositary or a nominee thereof or custodian therefor, and each
         such Global Security shall constitute a single Security for all
         purposes of this Indenture.

                  (ii) Except for exchanges of Global Securities for definitive,
         Non-global Securities at the sole discretion of the Company, no Global
         Security may be exchanged in whole or in part for Securities
         registered, and no transfer of a Global Security in whole or in part
         may be registered, in the name of any Person other than the Depositary
         for such Global Security or a nominee thereof unless (A) such
         Depositary (i) has notified the Company that it is unwilling or unable
         to continue as Depositary for such Global Security or (ii) has ceased
         to be a clearing agency registered as such under the Exchange Act or
         announces an intention permanently to cease business or does in fact do
         so or (B) there shall have occurred and be continuing an Event of
         Default with respect to such Global Security. In such event, if a
         successor Depositary for such Global Security is not appointed by the
         Company within 90 days after the Company receives such notice or
         becomes aware of such ineligibility, the Company will execute, and the
         Trustee, upon receipt of an Officers' Certificate directing the
         authentication and delivery of Securities, will authenticate and
         deliver, Securities, in any authorized denominations in an aggregate


                                      -31-

<PAGE>

         principal amount equal to the principal amount of such Global Security
         in exchange for such Global Security.

                  (iii) If any Global Security is to be exchanged for other
         Securities or canceled in whole, it shall be surrendered by or on
         behalf of the Depositary or its nominee to the Trustee, as Security
         Registrar, for exchange or cancellation, as provided in this Article
         III. If any Global Security is to be exchanged for other Securities or
         canceled in part, or if another Security is to be exchanged in whole or
         in part for a beneficial interest in any Global Security, in each case,
         as provided in Section 3.5, then either (A) such Global Security shall
         be so surrendered for exchange or cancellation, as provided in this
         Article III, or (B) the principal amount thereof shall be reduced or
         increased by an amount equal to the portion thereof to be so exchanged
         or canceled, or equal to the principal amount of such other Security to
         be so exchanged for a beneficial interest therein, as the case may be,
         by means of an appropriate adjustment made on the records of the
         Trustee, as Security Registrar, whereupon the Trustee, in accordance
         with the Applicable Procedures, shall instruct the Depositary or its
         authorized representative to make a corresponding adjustment to its
         records. Upon any such surrender or adjustment of a Global Security,
         the Trustee shall, subject to the provisions of Section 3.5 and as
         otherwise provided in this Article III, authenticate and deliver any
         Securities issuable in exchange for such Global Security (or any
         portion thereof) to or upon the order of, and registered in such names
         as may be directed by, the Depositary or its authorized representative.
         Upon the request of the Trustee in connection with the occurrence of
         any of the events specified in the preceding paragraph, the Company
         shall promptly make available to the Trustee a reasonable supply of
         Securities that are not in the form of Global Securities. The Trustee
         shall be entitled to rely upon any order, direction or request of the
         Depositary or its authorized representative which is given or made
         pursuant to this Article III if such order, direction or request is
         given or made in accordance with the Applicable Procedures.

                  (iv) Every Security authenticated and delivered upon 
         registration of transfer of, or in exchange for or in lieu of, a Global
         Security or any portion thereof, whether pursuant to this Article III 
         or otherwise, shall be authenticated and delivered in the form of, and
         shall be, a registered Global Security, unless such Security is 
         registered in the name of a Person other than the Depositary for such 
         Global Security or a nominee thereof, in which case such Security shall
         be authenticated and delivered in definitive, fully registered form, 
         without interest coupons. 

                  (v) The Depositary or its nominee, as registered owner of a
         Global Security, shall be the Holder of such Global Security for all
         purposes under the Indenture and the Securities, and owners of
         beneficial interests in a Global Security shall hold such interests
         pursuant to the Applicable Procedures. Accordingly, any such owner's
         beneficial interest in a Global Security will be shown only on, and the
         transfer of such interest shall be effected only through, records
         maintained by the Depositary or its nominee or its Agent Members and
         such owners of beneficial interests in a Global Security will not be
         considered the owners or holders thereof.


                                      -32-

<PAGE>

         (2) Pending the preparation of definitive Securities, the Company may
execute, and upon Company Order the Trustee shall authenticate and make
available for delivery, temporary Securities which are printed, lithographed,
typewritten, mimeographed or otherwise produced, in any authorized denomination,
substantially of the tenor of the definitive Securities in lieu of which they
are issued and with such appropriate insertions, omissions, substitutions and
other variations as the officers executing such Securities may determine, as
evidenced by their execution of such Securities. If temporary Securities are
issued, the Company will cause definitive Securities to be prepared without
unreasonable delay. After the preparation of definitive Securities, the
temporary Securities shall be exchangeable for definitive Securities upon
surrender of the temporary Securities at any office or agency of the Company
designated pursuant to Section 10.2, without charge to the Holder. Upon
surrender for cancellation of any one or more temporary Securities the Company
shall execute and the Trustee shall authenticate and make available for delivery
in exchange therefor a like principal amount of definitive Securities of
authorized denominations. Until so exchanged the temporary Securities shall in
all respects be entitled to the same benefits under this Indenture as definitive
Securities.

         SECTION 3.5  REGISTRATION; REGISTRATION OF TRANSFER AND EXCHANGE;
RESTRICTIONS ON TRANSFER.

         The Company shall cause to be kept at the Corporate Trust Office of the
Trustee a register (the register maintained in such office and in any other
office or agency of the Company designated pursuant to Section 10.2 being herein
sometimes collectively referred to as the "Security Register") in which, subject
to such reasonable regulations as it may prescribe, the Company shall provide
for the registration of Securities and of transfers of Securities. The Trustee
is hereby appointed "Security Registrar" for the purpose of registering
Securities and transfers and exchanges of Securities as herein provided.

         Upon surrender for registration of transfer of any Security at an
office or agency of the Company designated pursuant to Section 10.2 for such
purpose, the Company shall execute, and the Trustee shall authenticate and
deliver, in the name of the designated transferee or transferees, one or more
new Securities of any authorized denominations and of a like aggregate principal
amount and bearing such restrictive legends as may be required by this
Indenture.

         At the option of the Holder, and subject to the other provisions of
this Section 3.5, Securities may be exchanged for other Securities of any
authorized denomination and of a like aggregate principal amount, upon surrender
of the Securities to be exchanged at any such office or agency. Whenever any
Securities are so surrendered for exchange, and subject to the other provisions
of this Section 3.5, the Company shall execute, and the Trustee shall
authenticate and deliver, the Securities which the Holder making the exchange is
entitled to receive. Every Security presented or surrendered for registration of
transfer or for exchange shall (if so required by the Company or the Security
Registrar) be duly endorsed, or be accompanied by a written instrument of
transfer in form satisfactory to the Company, the Trustee and the Security
Registrar duly executed, by the Holder thereof or his attorney duly authorized
in writing. All Securities issued upon any registration of transfer or exchange
of Securities shall be the valid obligations of


                                      -33-

<PAGE>

the Company, evidencing the same debt and entitled to the same benefits under
this Indenture as the Securities surrendered upon such registration of transfer
or exchange.

         No service charge shall be made to a Holder for any registration of
transfer or exchange of Securities except as provided in Section 3.6, but the
Company may require payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in connection with any registration of
transfer or exchange of Securities, other than exchanges pursuant to Section
3.4, 8.5[, 12.2](39) or 14.3 (other than where the shares of Common Stock are to
be issued or delivered in a name other than that of the Holder of the Security)
not involving any transfer and other than any stamp and other duties, if any,
which may be imposed in connection with any such transfer or exchange by the
United States or any political subdivision thereof or therein, which shall be
paid by the Company.

         Each Holder of a Security agrees to indemnify the Company and the 
Trustee against any liability that may result from the transfer, exchange or 
assignment of such Holder's Security in violation of any provision of this 
Indenture and/or applicable United States Federal or state securities law.

         The Trustee shall have no obligation or duty to monitor, determine 
or inquire as to compliance with any restrictions on transfer imposed under 
this Indenture or under applicable law with respect to any transfer of any 
interest in any Security (including any transfers between or among Depositary 
Participants or beneficial owners of interest in any Global Security) other 
than to require delivery of such certificates and other documentation or 
evidence as are expressly required by, and to do so if and when expressly 
required by the terms of, this Indenture, and to examine the same to 
determine substantial compliance as to form with the express requirements 
hereof.

         In the event of a redemption of the Securities, neither the Company nor
the Securities Registrar will be required (a) to register the transfer of or
exchange Securities for a period of 15 days immediately preceding the date
notice is given identifying the serial numbers of the Securities called for such
redemption or (b) to register the transfer of or exchange any Security, or
portion thereof, called for redemption.

         SECTION 3.6  MUTILATED, DESTROYED, LOST OR STOLEN SECURITIES.

         If any mutilated Security is surrendered to the Trustee, the Company
shall execute and the Trustee shall authenticate and deliver in exchange
therefor a new Security of like tenor and principal amount and bearing a number
not contemporaneously outstanding.

         If there shall be delivered to the Company and to the Trustee:

         (1) evidence to their satisfaction of the destruction, loss or theft of
any Security, and

         (2) such security or indemnity as may be satisfactory to the Company
and the Trustee to save each of them and any agent of either of them harmless,
then, in the absence of actual notice to the Company or the Trustee that such
Security has been acquired by a bona fide purchaser, the Company shall execute
and the Trustee shall authenticate and deliver, in lieu of any such destroyed,
lost or stolen Security, a new Security of like tenor and principal amount and
bearing a number not contemporaneously outstanding.

         In case any such mutilated, destroyed, lost or stolen Security has
become or is about to become due and payable, the Company in its discretion 
[, but subject to any conversion rights,](40) may, instead of issuing a new
Security, pay such Security, upon satisfaction of the conditions set forth in
the preceding paragraph.


----------
         (39) INSERT IF SECURITIES ARE CONVERTIBLE

         (40) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -34-

<PAGE>

         Upon the issuance of any new Security under this Section 3.6, the
Company may require the payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in relation thereto (other than any
stamp and other duties, if any, which may be imposed in connection therewith by
the United States or any political subdivision thereof or therein, which shall
be paid by the Company) and any other expenses (including the fees and expenses
of the Trustee) connected therewith.

         Every new Security issued pursuant to this Section 3.6 in lieu of any
mutilated, destroyed, lost or stolen Security shall constitute an original
additional contractual obligation of the Company, whether or not the mutilated,
destroyed, lost or stolen Security shall be at any time enforceable by anyone,
and such new Security shall be entitled to all the benefits of this Indenture
equally and proportionately with any and all other Securities duly issued
hereunder.

         The provisions of this Section 3.6 are exclusive and shall preclude (to
the extent lawful) all other rights and remedies of any Holder with respect to
the replacement or payment of mutilated, destroyed, lost or stolen Securities.

         SECTION 3.7  PAYMENT OF INTEREST; INTEREST RIGHTS PRESERVED.

         Interest on any Security which is payable, and is punctually paid or
duly provided for, on any Interest Payment Date shall be paid to the Person in
whose name that Security (or one or more Predecessor Securities) is registered
at the close of business on the Regular Record Date for such interest.

         Any interest on any Security which is payable, but is not punctually
paid or duly provided for, on any Interest Payment Date (herein called
"Defaulted Interest") shall forthwith cease to be payable to the Holder on the
relevant Regular Record Date by virtue of having been such Holder, and such
Defaulted Interest may be paid by the Company, at its election in each case, as
provided in clause (1) or (2) below:

         (1) The Company may elect to make payment of any Defaulted Interest to
the Persons in whose names the Securities (or their respective Predecessor
Securities) are registered at the close of business on a Special Record Date for
the payment of such Defaulted Interest, which shall be fixed in the following
manner. The Company shall notify the Trustee in writing of the amount of
Defaulted Interest proposed to be paid on each Security, the date of the
proposed payment and the Special Record Date, and at the same time the Company
shall deposit with the Trustee an amount of money equal to the aggregate amount
proposed to be paid in respect of such Defaulted Interest or shall make
arrangements satisfactory to the Trustee for such deposit prior to the date of
the proposed payment, such money when deposited to be held in trust for the
benefit of the Persons entitled to such Defaulted Interest as in this clause
provided. The Special Record Date for the payment of such Defaulted Interest
shall be not more than 15 days and not less than 10 days prior to the date of
the proposed payment and not less than 10 days after the receipt by the Trustee
of the notice of the proposed payment. The Trustee, in the name and at the


                                      -35-

<PAGE>

expense of the Company, shall cause notice of the proposed payment of such
Defaulted Interest and the Special Record Date therefor to be mailed,
first-class postage prepaid, to each Holder at such Holder's address as it
appears in the Security Register, not less than 10 days prior to such Special
Record Date. Notice of the proposed payment of such Defaulted Interest and the
Special Record Date therefor having been so mailed, such Defaulted Interest
shall be paid to the Persons in whose names the Securities (or their respective
Predecessor Securities) are registered at the close of business on such Special
Record Date and shall no longer be payable pursuant to the following clause (2).

         (2) The Company may make payment of any Defaulted Interest in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Securities may be listed, and upon such notice as may be required
by such exchange, if, after notice given by the Company to the Trustee of the
proposed payment pursuant to this clause, such manner of payment shall be deemed
practicable by the Trustee.

         Subject to the foregoing provisions of this Section and Section 3.5,
each Security delivered under this Indenture upon registration of transfer of or
in exchange for or in lieu of any other Security shall carry the rights to
interest accrued and unpaid, and to accrue, which were carried by such other
Security.

         [Interest on any Security which is converted in accordance with Section
12.2 during a Record Date Period shall be payable in accordance with the
provisions of Section 12.2.](41)

         SECTION 3.8  PERSONS DEEMED OWNERS.

         Prior to due presentment of a Security for registration of transfer,
the Company, the Trustee, any Paying Agent and any agent of the Company, the
Trustee or any Paying Agent may treat the Person in whose name such Security is
registered as the owner of such Security for the purpose of receiving payment of
principal of, premium, if any, and (subject to Section 3.7) interest on such
Security and for all other purposes whatsoever, whether or not such Security be
overdue, and neither the Company, the Trustee, any Paying Agent nor any agent of
the Company, the Trustee or any Paying Agent shall be affected by notice to the
contrary.

         SECTION 3.9  CANCELLATION.

         All Securities surrendered for payment, redemption, repurchase,
registration of transfer or exchange [or conversion](42) or any Securities that
the Company may have acquired in any manner whatsoever, shall, if surrendered to
any Person other than the Trustee, be delivered to the Trustee. All Securities
so delivered to the Trustee shall be canceled promptly by the Trustee. No
Securities shall be authenticated in lieu of or in exchange for any Securities
canceled as provided


----------
         (41) INSERT IF SECURITIES ARE CONVERTIBLE

         (42) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -36-

<PAGE>

in this Section 3.9. The Trustee shall dispose of all canceled Securities in
accordance with applicable law and its customary practices in effect from time
to time.

         SECTION 3.10 COMPUTATION OF INTEREST.

         Interest on the Securities shall be computed on the basis of a 360-day
year of twelve 30-day months.

         SECTION 3.11 CUSIP NUMBERS.

         The Company in issuing Securities may use "CUSIP" numbers (if then
generally in use) in addition to serial numbers; if so, the Trustee shall use
such CUSIP numbers in addition to serial numbers in notices of redemption and
repurchase as a convenience to Holders; provided that any such notice may state
that no representation is made as to the correctness of such CUSIP numbers
either as printed on the Securities or as contained in any notice of a
redemption or repurchase and that reliance may be placed only on the serial or
other identification numbers printed on the Securities, and any such redemption
or repurchase shall not be affected by any defect in or omission of such CUSIP
numbers. The Company will promptly notify the Trustee of any change in the 
CUSIP numbers.

                                   ARTICLE IV

                           SATISFACTION AND DISCHARGE

         SECTION 4.1  SATISFACTION AND DISCHARGE OF INDENTURE.

         This Indenture shall upon Company Request cease to be of further effect
(except as to any surviving rights of [conversion, or](43) registration of
transfer or exchange, or replacement of Securities herein expressly provided for
and the Company's obligations to the Trustee pursuant to Section 6.7), and the
Trustee, at the expense of the Company, shall execute proper instruments in form
and substance satisfactory to the Trustee acknowledging satisfaction and
discharge of this Indenture, when

         (1) either (i) all Securities theretofore authenticated and delivered
(other than (A) Securities which have been destroyed, lost or stolen and which
have been replaced or paid as provided in Section 3.6 and (B) Securities for
whose payment money has theretofore been deposited in trust or segregated and
held in trust by the Company and thereafter repaid to the Company or discharged
from such trust, as provided in Section 10.3) have been delivered to the Trustee
for cancellation; or (ii) all such Securities not theretofore delivered to the
Trustee or its agent for cancellation (other than Securities referred to in
clauses (A) and (B) of clause (1)(i) above) (a) have become due and payable, or
(b) will have become due and payable at their Stated Maturity within one year,
or (c) are to be called for redemption within one year under


----------
         (43) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -37-

<PAGE>

arrangements satisfactory to the Trustee for the giving of notice of redemption
by the Trustee in the name, and at the expense, of the Company, and the Company,
in the case of clause (a), (b) or (c) above, has deposited or caused to be
deposited with the Trustee as trust funds (immediately available to the Holders
in the case of clause (a)) in trust for the purpose an amount in cash sufficient
to pay and discharge the entire indebtedness on such Securities not theretofore
delivered to the Trustee for cancellation, for principal, premium, if any, and
interest to the date of such deposit (in the case of Securities which have
become due and payable) or to the Stated Maturity or Redemption Date, as the
case may be;

         (2) the Company has paid or caused to be paid all other sums payable
hereunder by the Company; and

         (3) the Company has delivered to the Trustee an Officers' Certificate
and an Opinion of Counsel, each stating that all conditions precedent herein
provided for relating to the satisfaction and discharge of this Indenture have
been complied with.

         Notwithstanding the satisfaction and discharge of this Indenture, the
obligations of the Company to the Trustee under Section 6.7, the obligations of
the Company to any Authenticating Agent under Section 6.12, the obligations of
the Trustee under Section 4.2 and the last paragraph of Section 10.3 and the
obligations of the Company and the Trustee under Section 3.5 [and Article
XII](44) shall survive. Funds held in trust pursuant to this Section are not
subject to the provisions of Article XIII.

         SECTION 4.2  APPLICATION OF TRUST MONEY.

         Subject to the provisions of the last paragraph of Section 10.3, all
money deposited with the Trustee pursuant to Section 4.1 and in accordance with
the provisions of Article XIII shall be held in trust for the sole benefit of
the Holders, and such monies shall be applied by the Trustee, in accordance with
the provisions of the Securities and this Indenture, to the payment, either
directly or through any Paying Agent (including the Company acting as its own
Paying Agent), to the Persons entitled thereto, of the principal, premium, if
any, and interest for whose payment such money has been deposited with the
Trustee.

         [All moneys deposited with the Trustee pursuant to Section 4.1 (and
held by it or any Paying Agent) for the payment of Securities subsequently
converted shall be returned to the Company upon Company Request.](45)


----------
         (44) INSERT IF SECURITIES ARE CONVERTIBLE

         (45) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -38-

<PAGE>

                                    ARTICLE V

                                    REMEDIES

         SECTION 5.1 EVENTS OF DEFAULT.

         "Event of Default", wherever used herein, means any one of the
following events (whatever the reason for such Event of Default and whether it
shall be occasioned by the provisions of Article XIII or be voluntary or
involuntary or be effected by operation of law or pursuant to any judgment,
decree or order of any court or any order, rule or regulation of any
administrative or governmental body):

         (1) default in the payment of the principal of or premium, if any, on
any Security at its Maturity; or

         (2) default in the payment of any interest upon any Security when it
becomes due and payable, and continuance of such default for a period of 30
days; or

         (3) failure by the Company to give a Company Notice in accordance with
Section 14.3; or

         (4) default in the performance, or breach, of any covenant or warranty
of the Company in this Indenture (other than a covenant or warranty a default in
the performance or breach of which is specifically dealt with elsewhere in this
Section), and continuance of such default or breach for a period of 60 days
after there has been given, by registered or certified mail, to the Company by
the Trustee or to the Company and the Trustee by the Holders of at least 25% in
principal amount of the Outstanding Securities a written notice specifying such
default or breach and requiring it to be remedied and stating that such notice
is a "Notice of Default" hereunder; or

         (5) a default in the payment when due (whether at stated maturity or
any acceleration thereof) of the principal of, or acceleration of, any
indebtedness under any bonds, debentures, notes or other evidences of
indebtedness for money borrowed (or guarantee thereof) by the Company or any
Significant Subsidiary or under any mortgage, indenture or instrument under
which there may be issued or by which there may be secured or evidenced any
indebtedness for money borrowed by the Company or any Significant Subsidiary (an
"Instrument") with an aggregate principal amount then outstanding in excess of
U.S. $10,000,000, whether such indebtedness now exists or shall hereafter be
created if such indebtedness is not discharged, or such acceleration is not
rescinded or annulled, within a period of 30 days after there shall have been
given, by registered or certified mail, to the Company by the Trustee or to the
Company and the Trustee by the Holders of at least 25% in principal amount of
the Outstanding Securities a written notice specifying such default and
requiring the Company to cause such indebtedness to be discharged or cause such
default to be cured or waived or such acceleration to be rescinded or annulled
and stating that such notice is a "Notice of Default" hereunder; or

         (6) the entry by a court having jurisdiction in the premises of (A) a
decree or order for relief in respect of the Company or any Significant
Subsidiary in an involuntary case or


                                      -39-

<PAGE>

proceeding under any applicable Federal or State bankruptcy, insolvency,
reorganization or other similar law or (B) a decree or order adjudging the
Company or any Significant Subsidiary a bankrupt or insolvent, or approving as
properly filed a petition seeking reorganization, arrangement, adjustment or
composition of or in respect of the Company or any Significant Subsidiary under
any applicable Federal or State law, or appointing a custodian, receiver,
liquidator, assignee, trustee, sequestrator or other similar official of the
Company or any Significant Subsidiary or of any substantial part of the property
of either, or ordering the winding up or liquidation of its affairs, and the
continuance of any such decree or order for relief or any such other decree or
order unstayed and in effect for a period of 60 consecutive days; or 

         (7) the commencement by the Company or any Significant Subsidiary of 
a voluntary case or proceeding under any applicable Federal or State 
bankruptcy, insolvency, reorganization or other similar law or of any other 
case or proceeding to be adjudicated a bankrupt or insolvent, or the consent 
by either to the entry of a decree or order for relief in respect of the 
Company or any Significant Subsidiary in an involuntary case or proceeding 
under any applicable Federal or State bankruptcy, insolvency, reorganization 
or other similar law or to the commencement of any bankruptcy or insolvency 
case or proceeding against either, or the filing by either of a petition or 
answer or consent seeking reorganization or similar relief under any 
applicable Federal or State law, or the consent by either to the filing of 
such petition or to the appointment of or taking possession by a custodian, 
receiver, liquidator, assignee, trustee, sequestrator or other similar 
official of the Company or any Significant Subsidiary or of any substantial 
part of the property of either, or the making by either of an assignment for 
the benefit of creditors, or the admission by either in writing of its 
inability to pay its debts generally as they become due, or the taking of 
corporate action by the Company or any Significant Subsidiary in furtherance 
of any such action.

         SECTION 5.2  ACCELERATION OF MATURITY; RESCISSION AND ANNULMENT.

         If an Event of Default (other than an Event of Default specified in
Section 5.1(6) or 5.1(7) with respect to the Company) occurs and is continuing,
then in every such case the Trustee or the Holders of not less than 25% in
principal amount of the Outstanding Securities may, subject to the provisions of
Article XIII, declare the principal of all the Securities to be due and payable
immediately, by a notice in writing to the Company (and to the Trustee if given
by the Holders), and upon any such declaration such principal amount and all
accrued interest thereon shall become immediately due and payable. If an Event
of Default specified in Section 5.1(6) or 5.1(7) with respect to the Company
occurs, the principal amount of, and accrued interest on, all the Securities
shall, subject to the provisions of Article XIII, ipso facto become immediately
due and payable without any declaration or other Act of the Holders or any act
on the part of the Trustee.

         At any time after such declaration of acceleration has been made and
before a judgment or decree for payment of the money due has been obtained by
the Trustee as hereinafter in this Article V provided, the Holders of a majority
in principal amount of the Outstanding Securities, by written notice to the
Company and the Trustee, may, on behalf of all Holders, rescind and annul such
declaration and its consequences if:


                                      -40-

<PAGE>

         (1) the Company has paid or deposited with the Trustee a sum sufficient
to pay

                  (i)   all overdue interest on all Securities;

                  (ii)  the principal of and premium, if any, on any Securities
         which have become due otherwise than by such declaration of
         acceleration and any interest thereon at the rate borne by the
         Securities;

                  (iii) to the extent permitted by applicable law, interest upon
         overdue interest at a rate of _____% per annum, and (iv) all sums paid
         or advanced by the Trustee hereunder and the reasonable compensation,
         expenses, disbursements and advances of the Trustee, its agents and its
         counsel;

         (2) all Events of Default, other than the nonpayment of the principal
of, and any premium and interest on, Securities which have become due solely by
such declaration of acceleration, have been cured or waived as provided in
Section 5.13; and

         (3) such rescission and annulment would not conflict with any judgment
or decree issued in appropriate judicial proceedings regarding the payment by
the Trustee to the Holders of the amounts referred to in 5.2(1).

         No rescission or annulment referred to above shall affect any
subsequent default or impair any right consequent thereon.

         SECTION 5.3  COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY
TRUSTEE.

         The Company covenants that if:

         (1) default is made in the payment of any interest on any Security when
it becomes due and payable and such default continues for a period of 30 days,
or

         (2) default is made in the payment of the principal of or premium, if
any, on any Security at the Maturity thereof,

the Company will, upon demand of the Trustee but subject to the provisions of
Article XIII pay to it, for the benefit of the Holders of such Securities the
whole amount then due and payable on such Securities for principal and interest
and interest on any overdue principal and premium, if any, and, to the extent
permitted by applicable law, on any overdue interest, at a rate of _____% per
annum, and in addition thereto, such further amount as shall be sufficient to
cover the reasonable costs and expenses of collection, including the reasonable
compensation, expenses, disbursements and advances of the Trustee, its agents
and its counsel.


                                      -41-

<PAGE>

         If the Company fails to pay such amounts forthwith upon such demand,
the Trustee, in its own name and as trustee of an express trust, may institute a
judicial proceeding for the collection of the sums so due and unpaid, may
prosecute such proceeding to judgment or final decree and may enforce the same
against the Company or any other obligor upon the Securities and collect the
moneys adjudged or decreed to be payable in the manner provided by law out of
the property of the Company or any other obligor upon the Securities, wherever
situated.

         If an Event of Default occurs and is continuing, the Trustee may in its
discretion proceed to protect and enforce its rights and the rights of the
Holders by such appropriate judicial proceedings as the Trustee shall deem most
effectual to protect and enforce any such rights, whether for the specific
enforcement of any covenant or agreement in this Indenture or in aid of the
Exercise of any power granted herein, or to enforce any other proper remedy.

         SECTION 5.4  TRUSTEE MAY FILE PROOFS OF CLAIM.

         In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relative to the Company or any other obligor upon the
Securities or the property of the Company or of such other obligor or the
creditors of either, the Trustee (irrespective of whether the principal of, and
any interest on, the Securities shall then be due and payable as therein
expressed or by declaration or otherwise and irrespective of whether the Trustee
shall have made any demand on the Company for the payment of overdue principal
or interest) shall be entitled and empowered, by intervention in such proceeding
or otherwise,

         (1) to file and prove a claim for the whole amount of principal,
premium, if any, and interest owing and unpaid in respect of the Securities and
take such other actions, including participating as a member, voting or
otherwise, of any official committee of creditors appointed in such matter, and
to file such other papers or documents, in each of the foregoing cases, as may
be necessary or advisable in order to have the claims of the Trustee (including
any claim for the reasonable compensation, expenses, disbursements and advances
of the Trustee, its agents and its counsel) and of the Holders allowed in such
judicial proceeding, and

         (2) to collect and receive any moneys or other property payable or
deliverable on any such claim and to distribute the same; and any custodian,
receiver, assignee, trustee, liquidator, sequestrator or other similar official
in any such judicial proceeding is hereby authorized by each Holder to make such
payments to the Trustee and, in the event that the Trustee shall consent to the
making of such payments directly to the Holders to pay to the Trustee any amount
due to it for the reasonable compensation, expenses, disbursements and advances
of the Trustee, its agents and its counsel and any other amounts due the Trustee
under Section 6.7.

         Nothing herein contained shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder any plan of
reorganization, arrangement, adjustment or composition affecting the Securities
or the rights of any Holder thereof or to authorize the Trustee to vote in
respect of the claim of any Holder in any such proceeding;


                                      -42-

<PAGE>

provided, however, that the Trustee may, on behalf of such Holders, vote for the
election of a trustee in bankruptcy or similar official.

         SECTION 5.5  TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF
SECURITIES.

         All rights of action and claims under this Indenture or the Securities
may be prosecuted and enforced by the Trustee without the possession of any of
the Securities or the production thereof in any proceeding relating thereto, and
any such proceeding instituted by the Trustee shall be brought in its own name
as trustee of an express trust, and any recovery of judgment shall, after
provision for the payment of the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and its counsel, be for
the ratable benefit of the Holders of the Securities in respect of which
judgment has been recovered.

         SECTION 5.6  APPLICATION OF MONEY COLLECTED.

         Subject to Article XIII, any money collected by the Trustee pursuant to
this Article V shall be applied in the following order, at the date or dates
fixed by the Trustee and, in case of the distribution of such money on account
of principal, premium, if any, or interest, upon presentation of the Securities
and the notation thereon of the payment if only partially paid and upon
surrender thereof if fully paid:

         FIRST:  To the payment of all amounts due the Trustee under Section
6.7;

         SECOND: To the payment of the amounts then due and unpaid for principal
of, premium, if any, or interest on, the Securities in respect of which or for
the benefit of which such money has been collected, ratably, without preference
or priority of any kind, according to the amounts due and payable on such
Securities for principal, premium, if any, and interest, respectively;

         THIRD:  To such other Person or Persons, if any, to the extent entitled
thereto; and

         FOURTH:  Any remaining amounts shall be repaid to the Company.

         SECTION 5.7 LIMITATION ON SUITS.

         No Holder of any Security shall have any right to institute any
proceeding, judicial or otherwise, with respect to this Indenture, or for the
appointment of a receiver or trustee, or for any other remedy hereunder, unless:

         (1) such Holder has previously given written notice to the Trustee of a
continuing Event of Default;


                                      -43-

<PAGE>

         (2) the Holders of not less than 25% in principal amount of the
Outstanding Securities shall have made written request to the Trustee to
institute proceedings in respect of such Event of Default in its own name as
Trustee hereunder;

         (3) such Holder or Holders have offered to the Trustee indemnity 
reasonably satisfactory to the Trustee against the costs, expenses and 
liabilities to be incurred in compliance with such request;

         (4) the Trustee for 60 days after its receipt of such notice, request
and offer of indemnity has failed to institute any such proceeding; and

         (5) no direction inconsistent with such written request has been given
to the Trustee during such 60 day period by the Holders of a majority in
principal amount of the Outstanding Securities; it being understood and intended
that no one or more of such Holders shall have any right in any manner whatever
by virtue of, or by availing of, any provision of this Indenture to affect,
disturb or prejudice the rights of any other of such Holders, or to obtain or
seek to obtain priority or preference over any other of such Holders or to
enforce any right under this Indenture, except in the manner herein provided and
for the equal and ratable benefit of all such Holders.

         SECTION 5.8  UNCONDITIONAL RIGHT OF HOLDERS TO RECEIVE PRINCIPAL,
PREMIUM AND INTEREST [AND TO CONVERT.](46)

         Notwithstanding any other provision of this Indenture, but subject to
the provisions of Article XIII, the Holder of any Security shall have the right,
which is absolute and unconditional, to receive payment of the principal of,
premium, if any, and (subject to Section 3.7) interest on such Security on the
respective Stated Maturities expressed in such Security (or, in the case of
redemption or repurchase, on the Redemption Date or Repurchase Date, as the case
may be), [and to convert such Security in accordance with Article XII,](47) and
to institute suit for the enforcement of any such payment [and right to
convert](48), and such rights shall not be impaired without the consent of such
Holder.

         SECTION 5.9  RESTORATION OF RIGHTS AND REMEDIES.

         If the Trustee or any Holder has instituted any proceeding to enforce
any right or remedy under this Indenture and such proceeding has been
discontinued or abandoned for any reason, or has been determined adversely to
the Trustee or to such Holder, then and in every such case, subject to any
determination in such proceeding, the Company, the Trustee and the Holders shall
be restored severally and respectively to their former positions hereunder and
thereafter all rights


----------
         (46) INSERT IF SECURITIES ARE CONVERTIBLE

         (47) INSERT IF SECURITIES ARE CONVERTIBLE

         (48) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -44-

<PAGE>

and remedies of the Trustee and such Holders shall continue as though no such
proceeding had been instituted.

         SECTION 5.10  RIGHTS AND REMEDIES CUMULATIVE.

         Except as otherwise provided with respect to the replacement or payment
of mutilated, destroyed, lost or stolen Securities in the last paragraph of
Section 3.6, no right or remedy herein conferred upon or reserved to the Trustee
or to the Holders is intended to be exclusive of any other right or remedy, and
every right and remedy shall, to the extent permitted by law, be cumulative and
in addition to every other right and remedy given hereunder or now or hereafter
existing at law or in equity or otherwise. The assertion or employment of any
right or remedy hereunder, or otherwise, shall not prevent the concurrent
assertion or employment of any other appropriate right or remedy.

         SECTION 5.11  DELAY OR OMISSION NOT WAIVER.

         No delay or omission of the Trustee or of any Holder of any Security to
exercise any right or remedy accruing upon any Event of Default shall impair any
such right or remedy or constitute a waiver of any such Event of Default or any
acquiescence therein. Every right and remedy given by this Article V or by law
to the Trustee or to the Holders may be exercised from time to time, and as
often as may be deemed expedient, by the Trustee or (subject to the limitations
contained in this Indenture) by the Holders as the case may be.

         SECTION 5.12  CONTROL BY HOLDERS.

         Subject to Section 6.3, the Holders of a majority in principal amount
of the Outstanding Securities shall have the right to direct the time, method
and place of conducting any proceeding for any remedy available to the Trustee
or exercising any trust or power conferred on the Trustee, provided that

         (1) such direction shall not be in conflict with any rule of law or
with this Indenture, and

         (2) the Trustee may take any other action deemed proper by the Trustee
which is not inconsistent with such direction.

         SECTION 5.13  WAIVER OF PAST DEFAULTS.

         The Holders, either (i) through the written consent of not less than a
majority in principal amount of the Outstanding Securities or (ii) by the
adoption of a resolution, at a meeting of Holders of the Outstanding Securities
at which a quorum is present, by the Holders of at least 66 2/3% in principal
amount of the Outstanding Securities represented at such meeting, may on behalf
of the Holders of all the Securities waive any past default hereunder and its
consequences, except a default (A) in the payment of the principal of, premium,
if any, or interest on any


                                      -45-

<PAGE>

Security, or (B) in respect of a covenant or provision hereof which under
Article VIII cannot be modified or amended without the consent of the Holder of
each Outstanding Security affected.

         Upon any such waiver, such default shall cease to exist, and any Event
of Default arising therefrom shall be deemed to have been cured, for every
purpose of this Indenture; but no such waiver shall extend to any subsequent or
other default or impair any right consequent thereon.

         SECTION 5.14  UNDERTAKING FOR COSTS.

         All parties to this Indenture agree, and each Holder of any Security 
by his acceptance thereof shall be deemed to have agreed, that any court may 
in its discretion require, in any suit for the enforcement of any right or 
remedy under this Indenture, or in any suit against the Trustee for any 
action taken, suffered or omitted by it as Trustee, the filing by any party 
litigant in such suit of an undertaking to pay the costs of such suit, and 
that such court may in its discretion assess reasonable costs, including 
reasonable attorneys' fees and expenses, against any party litigant in such 
suit, having due regard to the merits and good faith of the claims or 
defenses made by such party litigant; but the provisions of this Section 5.14 
shall not apply to any suit instituted by the Company, to any suit instituted 
by the Trustee, to any suit instituted by any Holder, or group of Holders, 
holding in the aggregate more than 10% in principal amount of the Outstanding 
Securities, or to any suit instituted by any Holder of any Security for the 
enforcement of the payment of the principal of, premium, if any, or interest 
on any Security on or after the respective Stated Maturity or Maturities 
expressed in such Security (or, in the case of redemption or repurchase, on 
or after the Redemption Date or Repurchase Date, as the case may be) 
[or for the enforcement of the right to convert any Security in accordance with
Article XII.](49)

         SECTION 5.15  WAIVER OF STAY, USURY OR EXTENSION LAWS.

         The Company covenants (to the extent that it may lawfully do so) that
it will not at any time insist upon, or plead, or in any manner whatsoever claim
or take the benefit or advantage of, any stay, usury or extension law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture; and the Company (to the extent that it may
lawfully do so) hereby expressly waives all benefit or advantage of any such law
and covenants that it will not hinder, delay or impede by reason of such law the
execution of any power herein granted to the Trustee, but will suffer and permit
the execution of every such power as though no such law had been enacted.


----------
         (49) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -46-

<PAGE>

                                   ARTICLE VI

                                   THE TRUSTEE

         SECTION 6.1  CERTAIN DUTIES AND RESPONSIBILITIES.

         (1)      Except during the continuance of an Event of Default,

                  (i) the Trustee undertakes to perform such duties and only
         such duties as are specifically set forth in this Indenture, and no
         implied covenants or obligations shall be inferred or implied into 
         this Indenture against the Trustee; and

                  (ii) in the absence of bad faith on its part, the Trustee may
         conclusively rely, as to the truth of the statements and the
         correctness of the opinions expressed therein, upon certificates or
         opinions furnished to the Trustee and conforming to the requirements of
         this Indenture, but in the case of any such certificates or opinions
         which by any provision hereof are specifically required to be furnished
         to the Trustee, the Trustee shall be under a duty to examine the same
         to determine whether or not they conform to the requirements of this
         Indenture, but not to verify the contents thereof.

         (2) In case an Event of Default has occurred and is continuing, the
Trustee shall exercise such of the rights and powers vested in it by this
Indenture, and use the same degree of care and skill in their exercise, as a
prudent man would exercise or use under the circumstances in the conduct of his
own affairs.

         (3) No provision of this Indenture shall be construed to relieve the
Trustee from liability for its own negligent action, its own negligent failure
to act, or its own willful misconduct, except that:

                  (i) this paragraph (3) shall not be construed to limit the
         effect of paragraph (1) of this Section;

                  (ii) the Trustee shall not be liable for any error of judgment
         made in good faith by a Responsible Officer, unless it shall be proved
         that the Trustee was negligent in ascertaining the pertinent facts;

                  (iii) the Trustee shall not be liable with respect to any
         action taken or omitted to be taken by it in good faith in accordance
         with the direction of the Holders of a majority in principal amount of
         the Outstanding Securities relating to the time, method and place of
         conducting any proceeding for any remedy available to the Trustee, or
         exercising any trust or power conferred upon the Trustee, under this
         Indenture; and

                  (iv) no provision of this Indenture shall require the Trustee
         to expend or risk its own funds or otherwise incur any financial
         liability in the performance of any of its duties hereunder, or in the
         exercise of any of its rights or powers, if it shall have reasonable
         grounds for believing that repayment of such funds or adequate
         indemnity against such risk or liability is not reasonably assured to
         it.


                                      -47-

<PAGE>

         (4) Whether or not therein expressly so provided, every provision of
this Indenture relating to the conduct or affecting the liability of or
affording protection to the Trustee shall be subject to the provisions of this
Section.

         SECTION 6.2 NOTICE OF DEFAULTS.

         Within 90 days after the occurrence of any default hereunder as to
which a Responsible Officer of the Trustee has received written notice, the
Trustee shall give to all Holders, in the manner provided in Section 1.6, notice
of such default, unless such default shall have been cured or waived; provided,
however, that, except in the case of a default in the payment of the principal
of, premium, if any, or interest on any Security the Trustee shall be protected
in withholding such notice if and so long as the board of directors, the
executive committee or a trust committee of directors or Responsible Officers of
the Trustee in good faith determines that the withholding of such notice is in
the interest of the Holders; and provided, further, that in the case of any
default of the character specified in Section 5.1(4), no such notice to Holders
shall be given until at least 60 days after the occurrence thereof or, if
applicable, the cure period specified therein. For the purpose of this Section,
the term "default" means any event which is, or after notice or lapse of time or
both would become, an Event of Default.

         SECTION 6.3 CERTAIN RIGHTS OF TRUSTEE.

         Subject to the provisions of Section 6.1:

         (1) the Trustee may conclusively rely, and shall be protected in 
acting or refraining from acting, upon any resolution, Officers' Certificate, 
other certificate, statement, instrument, opinion, report, notice, request, 
direction, consent, order, bond, debenture, note, coupon, other evidence of 
indebtedness or other paper or document (collectively, the "Documents") 
believed by it to be genuine and to have been signed or presented by the 
proper party or parties, and the Trustee need not investigate any fact or 
matter stated in such Documents;

         (2) any request or direction of the Company mentioned herein shall be
sufficiently evidenced by a Company Request or Company Order and any resolution
of the Board of Directors shall be sufficiently evidenced by a Board Resolution;

         (3) whenever in the administration of this Indenture the Trustee 
shall deem it desirable that a matter be proved or established prior to 
taking, suffering or omitting any action hereunder, the Trustee (unless other 
evidence be herein specifically prescribed) may, in the absence of bad faith 
on its part, conclusively rely upon an Officers' Certificate;

         (4) the Trustee may consult with counsel of its selection and the
advice of such counsel or any Opinion of Counsel shall be full and complete
authorization and protection in respect of any action taken, suffered or omitted
by it hereunder in good faith and in reliance thereon;


                                      -48-

<PAGE>

         (5) the Trustee shall be under no obligation to exercise any of the 
rights or powers vested in it by this Indenture at the request or direction 
of any of the Holders pursuant to this Indenture, unless such Holders shall 
have offered to the Trustee security or indemnity reasonably satisfactory to 
the Trustee against the costs, expenses and liabilities which might be 
incurred by it in compliance with such request or direction;

         (6) the Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, direction, consent, order, bond, debenture,
note, coupon, other evidence of indebtedness or other paper or document, but the
Trustee may make such further inquiry or investigation into such facts or
matters as it may see fit, and, if the Trustee shall determine to make such
further inquiry or investigation, it shall be entitled to examine the books,
records and premises of the Company, personally or by agent or attorney and 
shall incur no liability or additional liability of any kind by reason of 
such inquiry or investigation; and Company shall reimburse the reasonable 
out-of-pocket costs actually incurred by the Trustee in connection with any 
such inquiry or investigation; 

         (7) the Trustee may execute any of the trusts or powers hereunder or
perform any duties hereunder either directly or by or through agents or
attorneys and the Trustee shall not be responsible for any misconduct or
negligence on the part of any agent or attorney appointed with due care by it
hereunder;

         (8) the Trustee shall not be liable for any action taken, suffered, 
or omitted to be taken by it in good faith and reasonably believed by it to 
be authorized or within the discretion or rights or powers conferred upon it 
by this Indenture;

         (9) the Trustee shall not be deemed to have notice of any Default or 
Event of Default unless a Responsible Officer of the Trustee has actual 
knowledge thereof or unless written notice of any event which is in fact such 
a default is received by the Trustee at the Corporate Trust Office of the 
Trustee, and such notice references the Securities and this Indenture;

         (10) the rights, privileges, protections, immunities and benefits 
given to the Trustee, including, without limitation, its right to be 
indemnified, are extended to, and shall be enforceable by, the Trustee in 
each of its capacities hereunder, and to each agent, custodian and other 
Person employed to act hereunder; and

         (11) the Trustee may request that the Company deliver an Officers' 
Certificate setting forth the names of individuals and/or titles of officers 
authorized at such time to take specified actions pursuant to this Indenture, 
which Officers' Certificate may be signed by any person authorized to sign an 
Officers' Certificate, including any person specified as so authorized in any 
such certificate previously delivered and not superseded.

         SECTION 6.4 NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF SECURITIES.

         The recitals contained herein and in the Securities (except the
Trustee's certificates of authentication) shall be taken as the statements of
the Company, and the Trustee assumes no responsibility for their correctness.
The Trustee makes no representations as to the validity or sufficiency of this
Indenture, of the Securities [or of the Common Stock issuable upon the
conversion of the Securities](50). The Trustee shall not be accountable for the
use or application by the Company of Securities or the proceeds thereof.

         SECTION 6.5  MAY HOLD SECURITIES, ACT AS TRUSTEE UNDER OTHER
INDENTURES.

         The Trustee, any Authenticating Agent, any Paying Agent[, any
Conversion Agent](51) or any other agent of the Company or the Trustee, in its
individual or any other capacity, may become the owner or pledgee of Securities
and may otherwise deal with the Company with the same rights it would have if it
were not Trustee, Authenticating Agent, Paying Agent[, Conversion Agent](52) or
such other agent.


----------
         (50) INSERT IF SECURITIES ARE CONVERTIBLE

         (51) INSERT IF SECURITIES ARE CONVERTIBLE

         (52) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -49-

<PAGE>

         The Trustee may become and act as trustee under other indentures under
which other securities, or certificates of interest or participation in other
securities, of the Company are outstanding in the same manner as if it were not
Trustee hereunder.

         SECTION 6.6  MONEY HELD IN TRUST.

         Money held by the Trustee in trust hereunder need not be segregated
from other funds except to the extent required by law. The Trustee shall be
under no liability for interest on any money received by it hereunder except as
otherwise agreed in writing with the Company.

         SECTION 6.7  COMPENSATION AND REIMBURSEMENT.

         The Company agrees:

         (1) to pay to the Trustee from time to time such reasonable
compensation as the Company and the Trustee shall from time to time agree in
writing for all services rendered by it hereunder (which compensation shall not
be limited by any provision of law in regard to the compensation of a trustee of
an express trust);

         (2) except as otherwise expressly provided herein, to reimburse the
Trustee upon its request for all reasonable expenses, disbursements and advances
incurred or made by the Trustee in accordance with any provision of this
Indenture (including the reasonable compensation and the expenses and
disbursements of its agents and counsel), except any such expense, disbursement
or advance as may be attributable to its negligence or bad faith; and

         (3) to indemnify the Trustee (and its directors, officers, employees 
and agents) for, and to hold it harmless against, any and all loss, 
liability, claim, damage or expense including taxes (other than taxes based 
on the income of the Trustee) incurred without negligence or bad faith on its 
part, arising out of or in connection with the acceptance or administration 
of this trust, including the reasonable costs, expenses and reasonable 
attorneys' fees of defending itself against any claim (whether asserted by 
the Company, any Holder or any other Person) or liability in connection with 
the exercise or performance of any of its powers or duties hereunder.

         When the Trustee incurs expenses or renders services in connection with
an Event of Default specified in Section 5.1(6) or Section 5.1(7), the expenses
(including the reasonable charges of its counsel) and the compensation for the
services are intended to constitute expenses of the administration under any
applicable Federal or state bankruptcy, insolvency or other similar law.

         The provisions of this Section shall survive the termination of this
Indenture or the earlier resignation or removal of the Trustee.


                                      -50-

<PAGE>

         SECTION 6.8  CORPORATE TRUSTEE REQUIRED; ELIGIBILITY.

         There shall at all times be a Trustee hereunder which shall be a Person
that is eligible pursuant to the Trust Indenture Act to act as such, having (or
being part of a holding company group with) a combined capital and surplus of at
least U.S. $50,000,000, subject to supervision or examination by federal or
state authority, and in good standing. The Trustee or an Affiliate of the
Trustee shall maintain an established place of business in the Borough of
Manhattan, The City of New York. If such corporation publishes reports of
condition at least annually, pursuant to law or to the requirements of said
supervising or examining authority, then for the purposes of this Section, the
combined capital and surplus of such corporation shall be deemed to be its
combined capital and surplus as set forth in its most recent report of condition
so published. If at any time the Trustee shall cease to be eligible in
accordance with the provisions of this Section, it shall resign immediately in
the manner and with the effect hereinafter specified in this Article and a
successor shall be appointed pursuant to Section 6.9.

         SECTION 6.9 RESIGNATION AND REMOVAL; APPOINTMENT OF SUCCESSOR.

         (1) No resignation or removal of the Trustee and no appointment of a
successor Trustee pursuant to this Article shall become effective until the
acceptance of appointment by the successor Trustee in accordance with the
applicable requirements of Section 6.10.

         (2) The Trustee may resign at any time by giving written notice thereof
to the Company. If the instrument of acceptance by a successor Trustee required
by Section 6.10 shall not have been delivered to the Trustee within 30 days
after the giving of such notice of resignation, the resigning Trustee may
petition any court of competent jurisdiction for the appointment of a successor
Trustee. The Company shall reimburse the reasonable out-of-pocket costs 
actually incurred by the Trustee in connection with any such position.

         (3) The Trustee may be removed at any time by an Act of the Holders 
of a majority in principal amount of the Outstanding Securities, delivered to 
the Trustee and the Company. If the instrument of acceptance by a successor 
Trustee required by Section 6.10 shall not have been delivered to the Trustee 
within 30 days after the giving of such notice of removal, the removed 
Trustee may petition any court of competent jurisdiction for the appointment 
of a successor Trustee. The Company shall reimburse the reasonable 
out-of-pocket costs actually incurred by the Trustee in connection with any 
such petition.

         (4)      If at any time:

                  (i) the Trustee shall cease to be eligible under Section 6.8
         and shall fail to resign after written request therefor by the Company
         or by any Holder who has been a bona fide Holder for at least six
         months,

                  (ii) the Trustee shall become incapable of acting or shall be
         adjudged a bankrupt or insolvent or a receiver of the Trustee or of its
         property shall be appointed or any public officer shall take charge or
         control of the Trustee or of its property or affairs for the purpose of
         rehabilitation, conservation or liquidation, or


                                      -51-

<PAGE>

                  (iii) the Trustee shall fail to comply with the provisions of
         Section 6.13 after written request therefor by the Company or any
         Holder who has been a bona fide Holder for at least six months, then,
         in any such case (i) the Company by a Board Resolution may remove the
         Trustee, or (ii) subject to Section 5.14, any Holder who has been a
         bona fide Holder for at least six months may, on behalf of himself and
         all others similarly situated, petition any court of competent
         jurisdiction for the removal of the Trustee and the appointment of a
         successor Trustee.

         (5) If the Trustee shall resign, be removed or become incapable of
acting, or if a vacancy shall occur in the office of Trustee for any cause, the
Company, by a Board Resolution, shall promptly appoint a successor Trustee and
shall comply with the applicable requirements of this Section and Section 6.10.
If, within one year after such resignation, removal or incapability, or the
occurrence of such vacancy, a successor Trustee shall be appointed by Act of the
Holders of a majority in principal amount of the Outstanding Securities
delivered to the Company and the retiring Trustee, the successor Trustee so
appointed shall, forthwith upon its acceptance of such appointment in accordance
with the applicable requirements of Section 6.10, become the successor Trustee
and supersede the successor Trustee appointed by the Company. If no successor
Trustee shall have been so appointed by the Company or the Holders and accepted
appointment in the manner required by this Section and Section 6.10, any Holder
who has been a bona fide Holder for at least six months may, on behalf of
himself and all others similarly situated, petition any court of competent
jurisdiction for the appointment of a successor Trustee.

         (6) The Company shall give notice of each resignation and each removal
of the Trustee and each appointment of a successor Trustee to all Holders in the
manner provided in Section 1.6. Each notice shall include the name of the
successor Trustee and the address of its Corporate Trust Office.

         SECTION 6.10 ACCEPTANCE OF APPOINTMENT BY SUCCESSOR.

         Every successor Trustee appointed hereunder shall execute, acknowledge
and deliver to the Company and to the retiring Trustee an instrument accepting
such appointment, and thereupon the resignation or removal of the retiring
Trustee shall become effective and such successor Trustee, without any further
act, deed or conveyance, shall become vested with all the rights, powers, trusts
and duties of the retiring Trustee; but, on the request of the Company or the
successor Trustee, such retiring Trustee shall, upon payment of its charges,
execute and deliver an instrument transferring to such successor Trustee all the
rights, powers and trusts of the retiring Trustee and shall duly assign,
transfer and deliver to such successor Trustee all property and money held by
such retiring Trustee hereunder. Upon request of any such successor Trustee, the
Company shall execute any and all instruments for more fully and certainly
vesting in and confirming to such successor Trustee all such rights, powers and
trusts.

         No successor Trustee shall accept its appointment unless at the time of
such acceptance such successor Trustee shall be eligible under this Article.


                                      -52-

<PAGE>

         SECTION 6.11  MERGER, CONVERSION, CONSOLIDATION OR SUCCESSION TO
BUSINESS.

         Any corporation into which the Trustee may be merged or converted or
with which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to all or substantially all of the corporate trust
business of the Trustee (including the trust created by this Indenture), shall
be the successor of the Trustee hereunder, provided such corporation shall be
otherwise eligible under this Article, without the execution or filing of any
paper or any further act on the part of any of the parties hereto. In case any
Securities shall have been authenticated, but not delivered, by the Trustee then
in office, any successor by merger, conversion or consolidation to such
authenticating Trustee may adopt such authentication and deliver the Securities
so authenticated with the same effect as if such successor Trustee had itself
authenticated such Securities.

         SECTION 6.12  AUTHENTICATING AGENTS.

         The Trustee may, with the consent of the Company, appoint an
Authenticating Agent or Agents acceptable to the Company with respect to the
Securities which shall be authorized to act on behalf of the Trustee to
authenticate Securities issued upon original issue and upon registration of
transfer or redemption, exchange or substitution pursuant to this Indenture.
Securities authenticated by an Authenticating Agent shall be entitled to the
benefits of this Indenture and shall be valid and obligatory for all purposes as
if authenticated by the Trustee hereunder, and every reference in this Indenture
to the authentication and delivery of Securities by the Trustee or the Trustee's
certificate of authentication shall be deemed to include authentication and
delivery on behalf of the Trustee by an Authenticating Agent and a certificate
of authentication executed on behalf of the Trustee by an Authenticating Agent.
Each Authenticating Agent shall be subject to acceptance by the Company and
shall at all times be a corporation organized and doing business under the laws
of the United States of America, any State thereof or the District of Columbia,
authorized under such laws to act as Authenticating Agent and subject to
supervision or examination by government or other fiscal authority. If at any
time an Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section 6.12, such Authenticating Agent shall resign
immediately in the manner and with the effect specified in this Section 6.12.

         Any corporation into which an Authenticating Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which such Authenticating Agent
shall be a party, or any corporation succeeding to the corporate agency or
corporate trust business of an Authenticating Agent, shall continue to be an
Authenticating Agent, provided such corporation shall be otherwise eligible
under this Section 6.12, without the execution or filing of any paper or any
further act on the part of the Trustee or the Authenticating Agent.

         An Authenticating Agent may resign at any time by giving written notice
thereof to the Trustee and to the Company. The Trustee may at any time terminate
the agency of an


                                      -53-

<PAGE>

Authenticating Agent by giving written notice thereof to such Authenticating
Agent and to the Company. Upon receiving such a notice of resignation or upon
such a termination, or in case at any time such Authenticating Agent shall cease
to be eligible in accordance with the provisions of this Section 6.12, the
Trustee may appoint a successor Authenticating Agent which shall be subject to
acceptance by the Company. Any successor Authenticating Agent upon acceptance of
its appointment hereunder shall become vested with all the rights, powers and
duties of its predecessor hereunder, with like effect as if originally named as
an Authenticating Agent. No successor Authenticating Agent shall be appointed
unless eligible under the provisions of this Section 6.12.

         The Company agrees to pay to each Authenticating Agent from time to
time reasonable compensation for its services under this Section 6.12.

         If an Authenticating Agent is appointed with respect to the Securities
pursuant to this Section 6.12, the Securities may have endorsed thereon, in
addition to or in lieu of the Trustee's certification of authentication, an
alternative certificate of authentication in the following form:

         This is one of the Securities referred to in the within-mentioned
Indenture.

                              __________________________________
                              as Trustee

                              By:_______________________________
                              As Authenticating Agent

                              By:_______________________________
                              Authorized Signatory

         SECTION 6.13   DISQUALIFICATION; CONFLICTING INTERESTS.

         If the Trustee has or shall acquire a conflicting interest within the
meaning of the Trust Indenture Act, the Trustee shall either eliminate such
interest or resign, to the extent and in the manner provided by, and subject to
the provisions of, the Trust Indenture Act and this Indenture.

         SECTION 6.14  PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY.

         If and when the Trustee shall be or become a creditor of the Company
(or any other obligor upon the Securities), the Trustee shall be subject to the
provisions of the Trust Indenture Act regarding the collection of claims against
the Company (or any such other obligor).


                                      -54-

<PAGE>

                                   ARTICLE VII

              CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

         SECTION 7.1  COMPANY MAY CONSOLIDATE, ETC., ONLY ON CERTAIN TERMS.

         The Company shall not consolidate with or merge into any other Person
or convey, transfer or lease all its properties and assets substantially as an
entirety to any Person, and the Company shall not permit any Person to
consolidate with or merge into the Company or convey, transfer, sell or lease
such Person's properties and assets substantially as an entirety to the Company
unless:

         (1) the Person formed by such consolidation or into or with which the
Company is merged or the Person to which the properties and assets of the
Company are so conveyed, transferred, sold or leased shall be a corporation,
limited liability company, partnership or trust organized and validly existing
under the laws of the United States of America, any State thereof or the
District of Columbia and, if other than the Company, shall expressly assume, by
an indenture supplemental hereto, executed and delivered to the Trustee, in form
satisfactory to the Trustee, the due and punctual payment of the principal of,
premium, if any, and interest on all of the Securities as applicable, and the
performance or observance of every covenant of this Indenture on the part of the
Company to be performed or observed [and shall have provided for conversion
rights in accordance with Article XII](53);

         (2) immediately after giving effect to such transaction, no Event of
Default, and no event that after notice or lapse of time or both, would become
an Event of Default, shall have occurred and be continuing; and

         (3) the Company has delivered to the Trustee an Officers' Certificate
and an Opinion of Counsel, each stating that such consolidation, merger,
conveyance, transfer or lease and, if a supplemental indenture is required in
connection with such transaction, such supplemental indenture comply with this
Article and that all conditions precedent herein provided for relating to such
transaction have been complied with, together with any documents required under
Section 8.3.

         SECTION 7.2  SUCCESSOR SUBSTITUTED.

         Upon any consolidation of the Company with, or merger of the Company
into any other Person or any conveyance, transfer or lease of all or
substantially all the properties and assets of the Company in accordance with
Section 7.1, the successor Person formed by such consolidation or into or with
which the Company is merged or to which such conveyance, transfer or lease is
made shall succeed to, and be substituted for, and may exercise every right and
power of, the Company under this Indenture with the same effect as if such
successor Person had been named


----------
         (53) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -55-

<PAGE>

as the Company herein, and thereafter, except in the case of a lease, the
predecessor Person shall be relieved of all obligations and covenants under this
Indenture and the Securities.

                                  ARTICLE VIII

                             SUPPLEMENTAL INDENTURES

         SECTION 8.1  SUPPLEMENTAL INDENTURES WITHOUT CONSENT OF HOLDERS.

         Without the consent of any Holders, the Company, when authorized by 
a Board Resolution, and the Trustee, at any time and from time to time, may 
enter into one or more indentures supplemental in form reasonably 
satisfactory to the Trustee hereto for any of the following purposes:

         (1) to evidence the succession of another Person to the Company and the
assumption by any such successor of the covenants and obligations of the Company
herein and in the Securities as permitted by Article VII of this Indenture; or

         (2) to add to the covenants of the Company for the benefit of the
Holders or to surrender any right or power herein conferred upon the Company; or

         (3) to secure the Securities; or

         (4) [to make provision with respect to the conversion rights of Holders
pursuant to Section 12.11 or](54) to make provision with respect to the
repurchase rights of Holders pursuant to Section 14.5; or

         (5) to comply with the requirements of the Trust Indenture Act or the
rules and regulations of the Commission thereunder in order to effect or
maintain the qualification of this Indenture under the Trust Indenture Act, as
contemplated by this Indenture or otherwise; or

         (6) to evidence and provide for the acceptance of appointment hereunder
by a successor Trustee; or

         (7) to cure any ambiguity, to correct or supplement any provision
herein which may be inconsistent with any other provision herein or which is
otherwise defective, or to make any other provisions with respect to matters or
questions arising under this Indenture as the Company and the Trustee may deem
necessary or desirable, provided such action pursuant to this clause (8) shall
not adversely affect the interests of the Holders in any material respect.


----------
         (54) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -56-

<PAGE>

         Upon Company Request, accompanied by a Board Resolution authorizing the
execution of any such supplemental indenture, and subject to and upon receipt by
the Trustee of the documents described in Section 8.3 hereof, the Trustee shall
join with the Company in the execution of any supplemental indenture authorized
or permitted by the terms of this Indenture and to make any further appropriate
agreements and stipulations which may be therein contained.

         SECTION 8.2  SUPPLEMENTAL INDENTURES WITH CONSENT OF HOLDERS.

         With either (i) the written consent of the Holders of not less than a
majority in principal amount of the Outstanding Securities, by the Act of said
Holders delivered to the Company and the Trustee, or (ii) by the adoption of a
resolution, at a meeting of Holders of the Outstanding Securities at which a
quorum is present, by the Holders of at least ______% in principal amount of the
Outstanding Securities represented at such meeting, the Company, when authorized
by a Board Resolution, and the Trustee may enter into an indenture or indentures
supplemental hereto for the purpose of adding any provisions to or changing in
any manner or eliminating any of the provisions of this Indenture or of
modifying in any manner the rights of the Holders under this Indenture;
provided, however, that no such supplemental indenture shall, without the
consent or affirmative vote of the Holder of each Outstanding Security affected
thereby,

         (1) change the Stated Maturity of the principal of, or any installment
of interest on, any Security, or reduce the principal amount of, or the premium,
if any, or the rate of interest payable thereon, or reduce the amount payable
upon a redemption or mandatory repurchase, or change the coin or currency of
payment of the principal of, premium, if any, or interest on any Security
(including any payment of the Redemption Price or Repurchase Price in respect of
such Security) or impair the right to institute suit for the enforcement of any
payment in respect of any Security on or after the Stated Maturity thereof (or,
in the case of redemption or any repurchase, on or after the Redemption Date or
Repurchase Date, as the case may be) [or, except as permitted by Section 12.11,
adversely affect the right of Holders to convert any Security as provided in
Article XII](55); or

         (2) reduce the requirements of Section 9.4 for quorum or voting, or
reduce the percentage in principal amount of the Outstanding Securities the
consent of whose Holders is required for any such supplemental indenture or the
consent of whose Holders is required for any waiver (of compliance with certain
provisions of this Indenture or certain defaults hereunder and their
consequences) provided for in this Indenture; or

         (3) modify the obligation of the Company to maintain an office or
agency in the Borough of Manhattan, The City of New York, pursuant to Section
10.2; or

         (4) modify any of the provisions of this Section or Section 5.13,
except to increase any percentage contained herein or therein or to provide that
certain other provisions of this


----------
         (55) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -57-

<PAGE>

Indenture cannot be modified or waived without the consent of the Holder of each
Outstanding Security affected thereby; or

         (5) modify the provisions of Article XIV in a manner adverse to the
Holders.

         It shall not be necessary for any Act of Holders under this Section to
approve the particular form of any proposed supplemental indenture, but it shall
be sufficient if such Act shall approve the substance thereof.

         SECTION 8.3  EXECUTION OF SUPPLEMENTAL INDENTURES.

         In executing, or accepting the additional trusts created by, any 
supplemental indenture permitted by this Article or the modifications thereby 
of the trusts created by this Indenture, the Trustee shall be entitled to 
receive, and (subject to Sections 6.1 and 6.3) shall be fully protected in 
relying upon, an Opinion of Counsel and Officers' Certificate stating that 
the execution of such supplemental indenture is authorized or permitted by 
this Indenture, and that such supplemental indenture has been duly 
authorized, executed and delivered by the Company and constitutes a valid and 
legally binding obligation of the Company enforceable against the Company in 
accordance with its terms. The Trustee may, but shall not be obligated to, 
enter into any such supplemental indenture which affects the Trustee's own 
rights, duties or immunities under this Indenture or otherwise.

         SECTION 8.4  EFFECT OF SUPPLEMENTAL INDENTURES.

         Upon the execution of any supplemental indenture under this Article,
this Indenture shall be modified in accordance therewith, and such supplemental
indenture shall form a part of this Indenture for all purposes; and every Holder
theretofore or thereafter authenticated and delivered hereunder appertaining
thereto shall be bound thereby.

         SECTION 8.5  REFERENCE IN SECURITIES TO SUPPLEMENTAL INDENTURES.

         Securities authenticated and delivered after the execution of any
supplemental indenture pursuant to this Article may, and shall if required by
the Trustee, bear a notation in form approved by the Trustee as to any matter
provided for in such supplemental indenture. If the Company shall so determine,
new Securities so modified as to conform, in the opinion of the Company and the
Trustee, to any such supplemental indenture may be prepared and executed by the
Company and authenticated and delivered by the Trustee in exchange for
Outstanding Securities.

         SECTION 8.6  NOTICE OF SUPPLEMENTAL INDENTURES.

         Promptly after the execution by the Company and the Trustee of any
supplemental indenture pursuant to the provisions of Section 8.2, the Company
shall give notice to all Holders of such fact, setting forth in general terms
the substance of such supplemental indenture, in the


                                      -58-

<PAGE>

manner provided in Section 1.6. Any failure of the Company to give such notice,
or any defect therein, shall not in any way impair or affect the validity of any
such supplemental indenture.

                                   ARTICLE IX

                               MEETINGS OF HOLDERS

         SECTION 9.1  PURPOSES FOR WHICH MEETINGS MAY BE CALLED.

         A meeting of Holders may be called at any time and from time to time
pursuant to this Article to make, give or take any request, demand,
authorization, direction, notice, consent, waiver or other action provided by
this Indenture to be made, given or taken by Holders.

         SECTION 9.2  CALL, NOTICE AND PLACE OF MEETINGS.

         (1) The Trustee may at any time call a meeting of Holders for any
purpose specified in Section 9.1, to be held at such time and at such place in
the Borough of Manhattan, The City of New York, as the Trustee shall determine.
Notice of every meeting of Holders, setting forth the time and the place of such
meeting and in general terms the action proposed to be taken at such meeting,
shall be given, in the manner provided in Section 1.6, not less than 21 nor more
than 180 days prior to the date fixed for the meeting.

         (2) In case at any time the Company, pursuant to a Board Resolution, or
the Holders of at least 10% in principal amount of the Outstanding Securities
shall have requested the Trustee to call a meeting of the Holders for any
purpose specified in Section 9.1, by written request setting forth in reasonable
detail the action proposed to be taken at the meeting, and the Trustee shall not
have mailed the notice of such meeting within 21 days after receipt of such
request or shall not thereafter proceed to cause the meeting to be held as
provided herein, then the Company or the Holders in the amount specified, as the
case may be, may determine the time and the place in the Borough of Manhattan,
The City of New York, for such meeting and may call such meeting for such
purposes by giving notice thereof as provided in paragraph (1) of this Section.

         SECTION 9.3  PERSONS ENTITLED TO VOTE AT MEETINGS.

         To be entitled to vote at any meeting of Holders, a Person shall be (i)
a Holder of one or more Outstanding Securities, or (ii) a Person appointed by an
instrument in writing as proxy for a Holder or Holders of one or more
Outstanding Securities by such Holder or Holders. The only Persons who shall be
entitled to be present or to speak at any meeting of Holders shall be the
Persons entitled to vote at such meeting and their counsel, any representatives
of the Trustee and its counsel and any representatives of the Company and its
counsel.


                                      -59-

<PAGE>

         SECTION 9.4  QUORUM; ACTION.

         The Persons entitled to vote a majority in principal amount of the
Outstanding Securities shall constitute a quorum. In the absence of a quorum
within 30 minutes of the time appointed for any such meeting, the meeting shall,
if convened at the request of Holders, be dissolved. In any other case, the
meeting may be adjourned for a period of not less than 10 days as determined by
the chairman of the meeting prior to the adjournment of such meeting. In the
absence of a quorum at any such adjourned meeting, such adjourned meeting may be
further adjourned for a period not less than 10 days as determined by the
chairman of the meeting prior to the adjournment of such adjourned meeting
(subject to repeated applications of this sentence). Notice of the reconvening
of any adjourned meeting shall be given as provided in Section 9.2(1), except
that such notice need be given only once not less than five days prior to the
date on which the meeting is scheduled to be reconvened. Notice of the
reconvening of an adjourned meeting shall state expressly the percentage of the
principal amount of the Outstanding Securities which shall constitute a quorum.

         Subject to the foregoing, at the reconvening of any meeting adjourned
for a lack of a quorum, the Persons entitled to vote 25% in principal amount of
the Outstanding Securities at the time shall constitute a quorum for the taking
of any action set forth in the notice of the original meeting.

         At a meeting or an adjourned meeting duly reconvened and at which a
quorum is present as aforesaid, any resolution and all matters (except as
limited by the proviso to Section 8.2 and except to the extent Section 10.12
requires a different vote) shall be effectively passed and decided if passed or
decided by the lesser of (i) the Holders of not less than a majority in
principal amount of Outstanding Securities and (ii) the Persons entitled to vote
not less than 66 2/3% in aggregate principal amount of Outstanding Securities
represented and entitled to vote at such meeting.

         Any resolution passed or decisions taken at any meeting of Holders duly
held in accordance with this Section shall be binding on all the Holders whether
or not present or represented at the meeting. The Trustee shall, in the name and
at the expense of the Company, notify all the Holders of any such resolutions or
decisions pursuant to Section 1.6.

         SECTION 9.5  DETERMINATION OF VOTING RIGHTS; CONDUCT AND ADJOURNMENT OF
MEETINGS.

         (1) The Trustee may make such reasonable regulations as it may deem
advisable for any meeting of Holders in regard to proof of the holding of
Securities and of the appointment of proxies and in regard to the appointment
and duties of inspectors of votes, the submission and examination of proxies,
certificates and other evidence of the right to vote, and such other matters
concerning the conduct of the meeting as it shall deem appropriate. Except as
otherwise permitted or required by any such regulations, the holding of
Securities shall be proved in the manner specified in Section 1.4 and the
appointment of any proxy shall be proved in the manner specified in Section 1.4
or by having the signature of the Person executing the proxy guaranteed


                                      -60-

<PAGE>

by any bank, broker or other eligible institution participating in a recognized
medallion signature guarantee program.

         (2) The Trustee shall, by an instrument in writing, appoint a temporary
chairman (which may be the Trustee) of the meeting, unless the meeting shall
have been called by the Company or by Holders as provided in Section 9.2(1), in
which case the Company or the Holders calling the meeting, as the case may be,
shall in like manner appoint a temporary chairman. A permanent chairman and a
permanent secretary of the meeting shall be elected by vote of the Persons
entitled to vote a majority in principal amount of the Outstanding Securities
represented at the meeting.

         (3) At any meeting, each Holder or proxy shall be entitled to one vote
for each U.S.$1,000 principal amount of Securities held or represented by him;
provided, however, that no vote shall be cast or counted at any meeting in
respect of any Security challenged as not Outstanding and ruled by the chairman
of the meeting to be not Outstanding. The chairman of the meeting shall have no
right to vote, except as a Holder or proxy.

         (4) Any meeting of Holders duly called pursuant to Section 9.2 at which
a quorum is present may be adjourned from time to time by Persons entitled to
vote a majority in principal amount of the Outstanding Securities represented at
the meeting, and the meeting may be held as so adjourned without further notice.

         SECTION 9.6  COUNTING VOTES AND RECORDING ACTION OF MEETINGS.

         The vote upon any resolution submitted to any meeting of Holders shall
be by written ballots on which shall be subscribed the signatures of the Holders
or of their representatives by proxy and the principal amounts at Stated
Maturity and serial numbers of the Outstanding Securities held or represented by
them. The permanent chairman of the meeting shall appoint two inspectors of
votes who shall count all votes cast at the meeting for or against any
resolution and who shall make and file with the secretary of the meeting their
verified written reports in duplicate of all votes cast at the meeting. A
record, at least in duplicate, of the proceedings of each meeting of Holders
shall be prepared by the secretary of the meeting and there shall be attached to
said record the original reports of the inspectors of votes on any vote by
ballot taken thereat and affidavits by one or more Persons having knowledge of
the facts setting forth a copy of the notice of the meeting and showing that
said notice was given as provided in Section 9.2 and, if applicable, Section
9.4. Each copy shall be signed and verified by the affidavits of the permanent
chairman and secretary of the meeting and one such copy shall be delivered to
the Company and another to the Trustee to be preserved by the Trustee, the
latter to have attached thereto the ballots voted at the meeting. Any record so
signed and verified shall be conclusive evidence of the matters therein stated.


                                      -61-

<PAGE>

                                    ARTICLE X

                                    COVENANTS

         SECTION 10.1  PAYMENT OF PRINCIPAL, PREMIUM AND INTEREST.

         The Company covenants and agrees that it will duly and punctually 
pay or cause to be paid the principal of and premium, if any, and interest on 
the Securities in accordance with the terms of the Securities and this 
Indenture. The Company will deposit or cause to be deposited with the 
Trustee, no later than 10 a.m. New York time on the date of the Stated 
Maturity of any Security or no later than the opening of business on the due 
date for any installment of interest, all payments so due, which payments 
shall be in immediately available funds on the date of such Stated Maturity 
or due date, as the case may be.

         SECTION 10.2  MAINTENANCE OF OFFICES OR AGENCIES.

         The Company will maintain in the Borough of Manhattan, The City of New
York, an office or agency where the Securities may be surrendered for
registration of transfer or exchange or for presentation for payment or for
[conversion,](56) redemption or repurchase and where notices and demands to or
upon the Company in respect of the Securities and this Indenture may be served.
The Company will give prompt written notice to the Trustee of the location, and
any change in the location, of such office or agency not designated or appointed
by the Trustee. If at any time the Company shall fail to maintain any such
required office or agency or shall fail to furnish the Trustee with the address
thereof, such presentations, surrenders, notices and demands may be made or
served at the Corporate Trust Office or the office or agency of the Trustee in
the Borough of Manhattan, The City of New York.

         The Company may at any time and from time to time vary or terminate the
appointment of any such agent or appoint any additional agents for any or all of
such purposes; provided, however, that until all of the Securities have been
delivered to the Trustee for cancellation, or moneys sufficient to pay the
principal of, premium, if any, and interest on the Securities have been made
available for payment and either paid or returned to the Company pursuant to the
provisions of Section 10.3, the Company will maintain in the Borough of
Manhattan, The City of New York, an office or agency where Securities may be
presented or surrendered for payment [and conversion](57), which shall initially
be ___________________, where Securities may be surrendered for registration of
transfer or exchange and where notices and demands to or upon the Company in
respect of the Securities and this Indenture may be served. The Company will
give prompt written notice to the Trustee, and notice to the Holders in
accordance with Section 1.6, of the appointment or termination of any such
agents and of the location and any change in the location of any such office or
agency.


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         (57) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -62-

<PAGE>


         The Company hereby initially designates the Trustee as Paying Agent,
Security Registrar [and Conversion Agent](58), and each of the Corporate Trust
Office of the Trustee and the office or agency of the Trustee in the Borough of
Manhattan, The City of New York, located at______,
___________________________attention:___________________________________________
as one such office or agency of the Company for each of the aforesaid purposes.

         SECTION 10.3  MONEY FOR SECURITY PAYMENTS TO BE HELD IN TRUST.

         If the Company shall act as its own Paying Agent, it will, on or before
each due date of the principal of, premium, if any, or interest on any of the
Securities, segregate and hold in trust for the benefit of the Persons entitled
thereto a sum sufficient to pay the principal, premium, if any, or interest so
becoming due until such sums shall be paid to such Persons or otherwise disposed
of as herein provided and the Company will promptly notify the Trustee of its
action or failure so to act.

         Whenever the Company shall have one or more Paying Agents, it will, 
no later than 10 a.m. New York time on each due date of the principal of, 
premium, if any, or interest on any Securities, deposit with the Trustee a 
sum in funds immediately payable on the payment date sufficient to pay the 
principal, premium, if any, or interest so becoming due, such sum to be held 
for the benefit of the Persons entitled to such principal, premium, if any, 
or interest, and (unless such Paying Agent is the Trustee) the Company will 
promptly notify the Trustee of any failure so to act.

         The Company will cause each Paying Agent other than the Trustee to
execute and deliver to the Trustee an instrument in which such Paying Agent
shall agree with the Trustee, subject to the provisions of this Section, that
such Paying Agent will:

         (1) hold all sums held by it for the payment of the principal of,
premium, if any, or interest on Securities for the benefit of the Persons
entitled thereto until such sums shall be paid to such Persons or otherwise
disposed of as herein provided;

         (2) give the Trustee notice of any default by the Company (or any other
obligor upon the Securities) in the making of any payment of principal, premium,
if any, or interest; and

         (3) at any time during the continuance of any such default, upon the
written request of the Trustee, forthwith pay to the Trustee all sums so held by
such Paying Agent.

         Anything in this Section 10.3 to the contrary notwithstanding, the
Company may at any time, for the purpose of obtaining the satisfaction and
discharge of this Indenture or for any other purpose, pay, or by Company Order
direct any Paying Agent to pay, to the Trustee all sums held in trust by the
Company or such Paying Agent, such sums to be held by the Trustee upon the


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                                      -63-

<PAGE>

same trusts as those upon which such sums were held by the Company or such
Paying Agent; and, upon such payment by any Paying Agent to the Trustee, such
Paying Agent shall be released from all further liability with respect to such
money.

         Any money deposited with the Trustee or any Paying Agent, or then held
by the Company, in trust for the payment of the principal of, premium, if any,
or interest on any Security and remaining unclaimed for two years after such
principal, premium, if any, or interest has become due and payable shall be paid
to the Company on Company Request, or (if then held by the Company) shall be
discharged from such trust; and the Holder of such Security shall thereafter, as
an unsecured general creditor, look only to the Company for payment thereof, and
all liability of the Trustee or such Paying Agent with respect to such trust
money, and all liability of the Company as trustee thereof, shall thereupon
cease. The Company shall not be liable for any interest on the sums paid to it
pursuant to this paragraph and shall not be regarded as a trustee of such money.

         SECTION 10.4  EXISTENCE.

         Subject to Article VII, the Company will do or cause to be done all
things necessary to preserve and keep in full force and effect its existence,
rights (charter and statutory) and franchises; provided, however, that the
Company shall not be required to preserve any such right or franchise if the
Company shall determine that the preservation thereof is no longer desirable in
the conduct of the business of the Company and that the loss thereof is not
disadvantageous in any material respect to the Holders.

         SECTION 10.5  PAYMENT OF TAXES AND OTHER CLAIMS.

         The Company will pay or discharge, or cause to be paid or discharged,
before the same may become delinquent, (i) all taxes, assessments and
governmental charges levied or imposed upon the Company or any Significant
Subsidiary or upon the income, profits or property of the Company or any
Significant Subsidiary, (ii) all claims for labor, materials and supplies which,
if unpaid, might by law become a lien or charge upon the property of the Company
or any Significant Subsidiary, and (iii) all stamps and other duties, if any,
which may be imposed by the United States or any political subdivision thereof
or therein in connection with the issuance, transfer, exchange [or
conversion](59) of any Securities or with respect to this Indenture; provided,
however, that, in the case of clauses (i) and (ii), the Company shall not be
required to pay or discharge or cause to be paid or discharged any such tax,
assessment, charge or claim (A) if the failure to do so will not, in the
aggregate, have a material adverse impact on the Company, or (B) if the amount,
applicability or validity is being contested in good faith by appropriate
proceedings.


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                                      -64-

<PAGE>

         [SECTION 10.6  REGISTRATION AND LISTING.

         The Company (i) will effect all registrations with, and obtain all
approvals by, all governmental authorities that may be necessary under any
United States Federal or state law (including the Securities Act, the Exchange
Act and state securities and Blue Sky laws) before the shares of Common Stock
issuable upon conversion of Securities are issued and delivered, and qualified
or listed as contemplated by clause (ii); and (ii) will qualify the shares of
Common Stock required to be issued and delivered upon conversion of Securities,
prior to such issuance or delivery, for quotation on the Nasdaq National Market
or, if the Common Stock is not then quoted on the Nasdaq National Market, list
the Common Stock on each national securities exchange or quotation system on
which outstanding Common Stock is listed or quoted at the time of such
delivery.](60)

         SECTION 10.7  STATEMENT BY OFFICERS AS TO DEFAULT.

         The Company shall deliver to the Trustee, within 120 days after the end
of each fiscal year of the Company ending after the date hereof, an Officers'
Certificate, stating whether or not to the best knowledge of the signers thereof
the Company is in default in the performance and observance of any of the terms,
provisions and conditions of this Indenture (without regard to any period of
grace or requirement of notice provided hereunder) and, if the Company shall be
in default, specifying all such defaults and the nature and status thereof of
which they may have knowledge.

         The Company will deliver to the Trustee, forthwith upon becoming aware
of any default or any Event of Default under the Indenture, an Officers'
Certificate specifying with particularity such default or Event of Default and
further stating what action the Company has taken, is taking or proposes to take
with respect thereto. For the purpose of this Section, the term "default" means
any event which is, or after notice or lapse of time or both would become, an
Event of Default.

         Any notice required to be given under this Section 10.7 shall be
delivered to the Trustee at its Corporate Trust Office.

         SECTION 10.8  WAIVER OF CERTAIN COVENANTS.

         The Company may omit in any particular instance to comply with any
covenant or condition set forth in Sections 10.4 (other than with respect to the
existence of the Company (subject to Article VII)) and 10.5, inclusive (other
than a covenant or condition which under Article VIII cannot be modified or
amended without the consent of the Holder of each Outstanding Security
affected), if before the time for such compliance the Holders shall, through the
written consent of, or the adoption of a resolution at a meeting of Holders of
the Outstanding Securities at which a quorum is present by, not less than a
majority in principal amount of the Outstanding Securities, either waive such
compliance in such instance or generally waive


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                                      -65-

<PAGE>

compliance with such covenant or condition, but no such waiver shall extend to
or affect such covenant or condition except to the extent so expressly waived,
and, until such waiver shall become effective, the obligations of the Company
and the duties of the Trustee or any Paying [or Conversion](61) Agent in respect
of any such covenant or condition shall remain in full force and effect.

                                   ARTICLE XI

                            REDEMPTION OF SECURITIES

         SECTION 11.1 RIGHT OF REDEMPTION.

         The Securities may be redeemed in accordance with the provisions of the
form of Securities set forth in Section 2.2.

         SECTION 11.2  APPLICABILITY OF ARTICLE.

         Redemption of Securities at the election of the Company or otherwise,
as permitted or required by any provision of the Securities or this Indenture,
shall be made in accordance with such provision and this Article XI.

         SECTION 11.3  ELECTION TO REDEEM; NOTICE TO TRUSTEE.

         The election of the Company to redeem any Securities shall be evidenced
by a Board Resolution. In case of any redemption at the election of the Company
of any of the Securities, the Company shall, at least 45 days prior to the
Redemption Date fixed by the Company (unless a shorter notice shall be
satisfactory to the Trustee), notify the Trustee in writing of such Redemption
Date.

         SECTION 11.4  SELECTION BY TRUSTEE OF SECURITIES TO BE REDEEMED.

         If less than all the Securities are to be redeemed, the particular
Securities to be redeemed shall be selected by the Trustee within three Business
Days after it receives the notice described in 11.3, from the Outstanding
Securities not previously called for redemption, by such method as the Trustee
may deem fair and appropriate.

         [If any Security selected for partial redemption is converted in part
before termination of the conversion right with respect to the portion of the
Security so selected, the converted portion of such Security shall be deemed (so
far as may be) to be the portion selected for redemption. Securities which have
been converted during a selection of Securities to be redeemed may be


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                                      -66-

<PAGE>

treated by the Trustee as Outstanding for the purpose of such selection.](62)
The Trustee shall promptly notify the Company and each Security Registrar in
writing of the Securities selected for redemption and, in the case of any
Securities selected for partial redemption, the principal amount and certificate
numbers thereof to be redeemed.

         For all purposes of this Indenture, unless the context otherwise
requires, all provisions relating to the redemption of Securities shall relate,
in the case of any

         Securities redeemed or to be redeemed only in part, to the portion of
the principal amount of such Securities which has been or is to be redeemed.

         SECTION 11.5  NOTICE OF REDEMPTION.

         Notice of redemption shall be given in the manner provided in Section
1.6 to the Holders to be redeemed not less than 30 nor more than 60 days prior
to the Redemption Date, and such notice shall be irrevocable.

         All notices of redemption shall include the CUSIP number and state:

         (1) the Redemption Date;

         (2) the Redemption Price, and accrued interest, if any, to the
Redemption Date;

         (3) if less than all Outstanding Securities are to be redeemed, the
aggregate principal amount of Securities to be redeemed and the aggregate
principal amount of Securities which will be outstanding after such partial
redemption;

         (4) that on the Redemption Date the Redemption Price, and accrued
interest, if any, to the Redemption Date, will become due and payable upon each
such Security to be redeemed, and that interest thereon shall cease to accrue on
and after said date;

         [(5) the Conversion Rate, the date on which the right to convert the
Securities to be redeemed will terminate and the places where such Securities
may be surrendered for conversion;](63) and

         (6) the place or places where such Securities are to be surrendered for
payment of the Redemption Price and accrued interest, if any, to the Redemption
Date.


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         (63) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -67-

<PAGE>

         In case of a partial redemption, the notice shall specify the serial
and CUSIP numbers (if any) and the portions thereof called for redemption and
that transfers and exchanges may occur on or prior to the Redemption Date.

         Notice of redemption of Securities to be redeemed at the election of
the Company shall be given by the Company or, at the Company's written request,
by the Trustee in the name of and at the expense of the Company. Notice of
redemption of Securities to be redeemed at the election of the Company received
by the Trustee shall be given by the Trustee to each Paying Agent in the name of
and at the expense of the Company. Notice of redemption of the Securities to be
redeemed at the election of the Company shall also be given to one or more
nationally-recognized reporting institutions such as Bloomberg.

         SECTION 11.6  DEPOSIT OF REDEMPTION PRICE.

         Prior to 10 a.m. New York time on any Redemption Date, the Company 
shall deposit with the Trustee (or, if the Company is acting as its own 
Paying Agent, segregate and hold in trust as provided in Section 10.3) an 
amount of money (which shall be in immediately available funds on such 
Redemption Date) sufficient to pay the Redemption Price of, and (except if 
the Redemption Date shall be an Interest Payment Date) accrued interest to 
the Redemption Date on, all the Securities which are to be redeemed on that 
date [other than any Securities called for redemption on that date which 
have been converted prior to the date of such deposit](64).

         [If any Security called for redemption is converted, any money
deposited with the Trustee or so segregated and held in trust for the redemption
of such Security shall (subject to any right of the Holder of such Security or
any Predecessor Security to receive interest as provided in the last paragraph
of Section 3.7) be paid to the Company on Company Request or, if then held by
the Company, shall be discharged from such trust.](65)

         SECTION 11.7  SECURITIES PAYABLE ON REDEMPTION DATE.

         Notice of redemption having been given as aforesaid, the Securities so
to be redeemed shall, on the Redemption Date, become due and payable at the
Redemption Price therein specified and from and after such date (unless the
Company shall default in the payment of the Redemption Price, including accrued
interest) such Securities shall cease to bear interest. Upon surrender of any
Security for redemption in accordance with said notice, such Security shall be
paid by the Company at the Redemption Price together with accrued and unpaid
interest to the Redemption Date; provided, however, that installments of
interest on Securities whose Stated Maturity is on or prior to the Redemption
Date shall be payable to the Holders of such Securities, or one or more
Predecessor Securities, registered as such on the relevant Record Date according
to their terms and the provisions of Section 3.7.


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                                      -68-

<PAGE>

         If any Security called for redemption shall not be so paid upon
surrender thereof for redemption, the principal amount of, premium, if any, and,
to the extent permitted by applicable law, accrued interest on such Security
shall, until paid, bear interest from the Redemption Date at a rate of _____%
per annum [and such Security shall remain convertible](66) until the Redemption
Price of such Security (or portion thereof, as the case may be) shall have been
paid or duly provided for.

         Any Security which is to be redeemed only in part shall be surrendered
at the Corporate Trust Office or an office or agency of the Company designated
for that purpose pursuant to Section 10.2 (with, if the Company or the Trustee
so requires, due endorsement by, or a written instrument of transfer in form
satisfactory to the Company and the Trustee duly executed by, the Holder thereof
or his attorney duly authorized in writing), and the Company shall execute, and
the Trustee shall authenticate and make available for delivery to the Holder of
such Security without service charge, a new Security or Securities, of any
authorized denomination as requested by such Holder, in aggregate principal
amount equal to and in exchange for the unredeemed portion of the principal of
the Security so surrendered.

         [SECTION 11.8  CONVERSION ARRANGEMENT ON CALL FOR REDEMPTION.

         In connection with any redemption of Securities, the Company may 
arrange for the purchase and conversion of any Securities by an agreement 
with one or more investment bankers or other purchasers (the "Purchasers") to 
purchase such Securities by paying to the Trustee in trust for the Holders, 
on or before the Redemption Date, an amount not less than the applicable 
Redemption Price, together with interest accrued and unpaid to the Redemption 
Date, of such Securities. Notwithstanding anything to the contrary contained 
in this Article XI, the obligation of the Company to pay the Redemption 
Price, together with interest accrued and unpaid to the Redemption Date, 
shall be deemed to be satisfied and discharged to the extent such amount is 
so paid by such Purchasers. If such an agreement is entered into (a copy of 
which shall be filed with the Trustee prior to the close of business on the 
Business Day immediately prior to the Redemption Date), any Securities called 
for redemption that are not duly surrendered for conversion by the Holders 
thereof may, at the option of the Company, be deemed, to the fullest extent 
permitted by law, and consistent with any agreement or agreements with such 
Purchasers, to be acquired by such Purchasers from such Holders and 
(notwithstanding anything to the contrary contained in Article XII) 
surrendered by such Purchasers for conversion, all as of immediately prior to 
the close of business on the Redemption Date (and the right to convert any 
such Securities shall be extended through such time), subject to payment of 
the above amount as aforesaid. At the direction of the Company, the Trustee 
shall hold and dispose of any such amount paid to it by the Purchasers to the 
Holders in the same manner as it would monies deposited with it by the 
Company for the redemption of Securities. Without the Trustee's prior written 
consent, no arrangement between the Company and such Purchasers for the 
purchase and conversion of any Securities shall increase or otherwise affect 
any of the powers, duties, responsibilities or obligations of the Trustee as 
set forth in this Indenture, and the Company agrees to indemnify the Trustee 
from, and hold it harmless against, any and all loss, liability, claim, 
damage or expense arising out of or in connection with any such arrangement 
for the purchase and

----------
         (66) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -69-

<PAGE>

conversion of any Securities between the Company and such Purchasers, including
the costs and expenses, including reasonable legal fees, incurred by the Trustee
in the defense of any claim or liability arising out of or in connection with
the exercise or performance of any of its powers, duties, responsibilities or
obligations under this Indenture.](67)

                                  [ARTICLE XII

                            CONVERSION OF SECURITIES

         SECTION 12.1  CONVERSION PRIVILEGE AND CONVERSION RATE.

         Subject to and upon compliance with the provisions of this Article, at
the option of the Holder thereof, any Security may be converted into fully paid
and nonassessable shares (calculated as to each conversion to the nearest
1/100th of a share) of Common Stock of the Company at the Conversion Rate,
determined as hereinafter provided, in effect at the time of conversion. Such
conversion right shall commence upon the original issuance date of the
Securities and expire at the close of business on the date of Maturity, subject,
in the case of conversion of any Global Security, to any Applicable Procedures.
In case a Security or portion thereof is called for redemption at the election
of the Company or the Holder thereof exercises his right to require the Company
to repurchase the Security, such conversion right in respect of the Security, or
portion thereof so called, shall expire at the close of business on the Business
Day immediately preceding the Redemption Date or the Repurchase Date, as the
case may be, unless the Company defaults in making the payment due upon
redemption or repurchase, as the case may be (in each case subject as aforesaid
to any Applicable Procedures with respect to any Global Security).

         The rate at which shares of Common Stock shall be delivered upon
conversion (herein called the "Conversion Rate") shall be initially ______
shares of Common Stock for each U.S.$1,000 principal amount of Securities. The
Conversion Rate shall be adjusted in certain instances as provided in this
Article XII.

         SECTION 12.2  EXERCISE OF CONVERSION PRIVILEGE.

         In order to exercise the conversion privilege, the Holder of any
Security to be converted shall surrender such Security, duly endorsed in blank,
at any office or agency of the Company maintained for that purpose pursuant to
Section 10.2, accompanied by a duly signed conversion notice substantially in
the form set forth in Section 2.4 stating that the Holder elects to convert


----------
         (67) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -70-

<PAGE>

such Security or, if less than the entire principal amount thereof is to be
converted, the portion thereof to be converted. Each Security surrendered for
conversion (in whole or in part) during the Record Date Period shall (except in
the case of any Security or portion thereof which has been called for redemption
on a Redemption Date, or is repurchasable on a Repurchase Date, occurring, in
either case, within such Record Date Period and, as a result, the right to
convert would terminate in such period) be accompanied by payment in New York
Clearing House funds or other funds acceptable to the Company of an amount equal
to the interest payable on such Interest Payment Date on the principal amount of
such Security (or part thereof, as the case may be) being surrendered for
conversion. The interest so payable on such Interest Payment Date with respect
to any Security (or portion thereof, if applicable) which is surrendered for
conversion during the Record Date Period shall be paid to the Holder of such
Security as of such Regular Record Date in an amount equal to the interest that
would have been payable on such Security if such Security had been converted as
of the close of business on such Interest Payment Date. Interest payable in
respect of any Security surrendered for conversion on or after an Interest
Payment Date shall be paid to the Holder of such Security as of the next
preceding Regular Record Date, notwithstanding the exercise of the right of
conversion. Except as provided in this paragraph and subject to the last
paragraph of Section 3.7, no cash payment or adjustment shall be made upon any
conversion on account of any interest accrued from the Interest Payment Date
next preceding the conversion date, in respect of any Security (or part thereof,
as the case may be) surrendered for conversion, or on account of any dividends
on the Common Stock issued upon conversion. The Company's delivery to the Holder
of the number of shares of Common Stock (and cash in lieu of fractions thereof,
as provided in this Indenture) into which a Security is convertible will be
deemed to satisfy the Company's obligation to pay the principal amount of the
Security.

         Securities shall be deemed to have been converted immediately prior to
the close of business on the day of surrender of such Securities for conversion
in accordance with the foregoing provisions, and at such time the rights of the
Holders of such Securities as Holders shall cease, and the Person or Persons
entitled to receive the Common Stock issuable upon conversion shall be treated
for all purposes as the record holder or holders of such Common Stock at such
time. As promptly as practicable on or after the conversion date, the Company
shall issue and deliver to the Trustee, for delivery to the Holder, a
certificate or certificates for the number of full shares of Common Stock
issuable upon conversion, together with payment in lieu of any fraction of a
share, as provided in Section 12.3.

         In the case of any Security which is converted in part only, upon 
such conversion the Company shall execute and the Trustee shall authenticate 
and deliver to the Holder thereof, at the expense of the Company, a new 
Security or Securities of authorized denominations in an aggregate principal 
amount equal to the unconverted portion of the principal amount of such 
Security. A Security may be converted in part, but only if the principal 
amount of such Security to be converted is an integral multiple of U.S. 
$1,000 and the principal amount of such security to remain Outstanding after 
such conversion is an integral multiple of $1,000.

                                      -71-

<PAGE>

         SECTION 12.3  FRACTIONS OF SHARES.

         No fractional shares of Common Stock shall be issued upon conversion 
of any Security or Securities. If more than one Security shall be surrendered 
for conversion at one time by the same Holder, the number of full shares 
which shall be issuable upon conversion thereof shall be computed on the 
basis of the aggregate principal amount of the Securities (or specified 
portions thereof) so surrendered. Instead of any fractional share of Common 
Stock which would otherwise be issuable upon conversion of any Security or 
Securities (or specified portions thereof), the Company shall calculate and 
pay a cash adjustment in respect of such fraction (calculated to the nearest 
1/100th of a share) in an amount equal to the same fraction of the Closing 
Price Per Share at the close of business on the day of conversion.

         SECTION 12.4  ADJUSTMENT OF CONVERSION RATE.

         The Conversion Rate shall be subject to adjustments from time to time
as follows:

         (1) In case the Company shall pay or make a dividend or other
distribution on shares of any class of capital stock of the Company payable in
shares of Common Stock, the Conversion Rate in effect at the opening of business
on the day following the date fixed for the determination of stockholders
entitled to receive such dividend or other distribution shall be increased by
dividing such Conversion Rate by a fraction of which the numerator shall be the
number of shares of Common Stock outstanding at the close of business on the
date fixed for such determination and the denominator shall be the sum of such
number of shares and the total number of shares constituting such dividend or
other distribution, such increase to become effective immediately after the
opening of business on the day following the date fixed for such determination.
If, after any such date fixed for determination, any dividend or distribution is
not in fact paid, the Conversion Rate shall be immediately readjusted, effective
as of the date the Board of Directors determines not to pay such dividend or
distribution, to the Conversion Rate that would have been in effect if such
determination date had not been fixed. For the purposes of this paragraph (1),
the number of shares of Common Stock at any time outstanding shall not include
shares held in the treasury of the Company but shall include shares issuable in
respect of scrip certificates issued in lieu of fractions of shares of Common
Stock. The Company will not pay any dividend or make any distribution on shares
of Common Stock held in the treasury of the Company.

         (2) In case the Company shall issue rights, options or warrants to all
holders of its Common Stock entitling them to subscribe for or purchase shares
of Common Stock at a price per share less than the current market price per
share (determined as provided in paragraph (8) of this Section 12.4) of the
Common Stock on the date fixed for the determination of stockholders entitled to
receive such rights, options or warrants (other than any rights, options or
warrants that by their terms will also be issued to any Holder upon conversion
of a Security into shares of Common Stock without any action required by the
Company or any other Person), the Conversion Rate in effect at the opening of
business on the day following the date fixed for such determination shall be
increased by dividing such Conversion Rate by a fraction of which the


                                      -72-

<PAGE>

numerator shall be the number of shares of Common Stock outstanding at the close
of business on the date fixed for such determination plus the number of shares
of Common Stock which the aggregate of the offering price of the total number of
shares of Common Stock so offered for subscription or purchase would purchase at
such current market price and the denominator shall be the number of shares of
Common Stock outstanding at the close of business on the date fixed for such
determination plus the number of shares of Common Stock so offered for
subscription or purchase, such increase to become effective immediately after
the opening of business on the day following the date fixed for such
determination. If, after any such date fixed for determination, any such rights,
options or warrants are not in fact issued, or are not exercised prior to the
expiration thereof, the Conversion Rate shall be immediately readjusted,
effective as of the date such rights, options or warrants expire, or the date
the Board of Directors determines not to issue such rights, options or warrants,
to the Conversion Rate that would have been in effect if the unexercised rights,
options or warrants had never been granted or such determination date had not
been fixed, as the case may be. For the purposes of this paragraph (2), the
number of shares of Common Stock at any time outstanding shall not include
shares held in the treasury of the Company but shall include shares issuable in
respect of scrip certificates issued in lieu of fractions of shares of Common
Stock. The Company will not issue any rights, options or warrants in respect of
shares of Common Stock held in the treasury of the Company.

         (3) In case the outstanding shares of Common Stock shall be subdivided
into a greater number of shares of Common Stock, the Conversion Rate in effect
at the opening of business on the day following the day upon which such
subdivision becomes effective shall be proportionately increased, and,
conversely, in case the outstanding shares of Common Stock shall be combined
into a smaller number of shares of Common Stock, the Conversion Rate in effect
at the opening of business on the day following the day upon which such
subdivision or combination becomes effective shall be proportionately reduced,
such increase or reduction, as the case may be, to become effective immediately
after the opening of business on the day following the day upon which such
subdivision or combination becomes effective.

         (4) In case the Company shall, by dividend or otherwise, distribute to
all holders of its Common Stock evidences of its indebtedness, shares of any
class of capital stock or other property (including cash or assets or
securities, but excluding (i) any rights, options or warrants referred to in
paragraph (2) of this Section, (ii) any dividend or distribution paid
exclusively in cash, (iii) any dividend or distribution referred to in paragraph
(1) of this Section and (iv) any mergers or consolidations to which Section
12.11 applies), the Conversion Rate shall be adjusted so that the same shall
equal the rate determined by dividing the Conversion Rate in effect immediately
prior to the close of business on the date fixed for the determination of
stockholders entitled to receive such distribution by a fraction of which the
numerator shall be the current market price per share (determined as provided in
paragraph (8) of this Section 12.4) of the Common Stock on the date fixed for
such determination less the then fair market value (as determined by the Board
of Directors, whose determination shall be conclusive and described in a Board
Resolution filed with the Trustee) of the portion of the assets, shares or
evidences of indebtedness so distributed applicable to one share of Common Stock
and the denominator shall be such current market price per share of the Common
Stock, such adjustment to become


                                      -73-

<PAGE>

effective immediately prior to the opening of business on the day following the
date fixed for the determination of stockholders entitled to receive such
distribution. If, after any such date fixed for determination, any such
distribution is not in fact made, the Conversion Rate shall be immediately
readjusted, effective as of the date that the Board of Directors determines not
to make such distribution, to the Conversion Rate that would have been in effect
if such determination date had not been fixed.

         (5) In case the Company shall, by dividend or otherwise, distribute to
all holders of its Common Stock cash (excluding any cash that is distributed as
part of a distribution referred to in paragraph (4) of this Section or cash
distributed upon a merger or consolidation to which Section 12.11 applies) in an
aggregate amount that, combined together with (I) the aggregate amount of any
other cash distributions to all holders of its Common Stock made exclusively in
cash within the 365-day period preceding the date of payment of such
distribution and in respect of which no adjustment pursuant to this paragraph
(5) has been made and (II) the aggregate of any cash plus the fair market value
(as determined by the Board of Directors, whose determination shall be
conclusive and described in a Board Resolution) of consideration payable in
respect of any tender offer by the Company or any of its Subsidiaries for all or
any portion of the Common Stock concluded within the 365-day period preceding
the date of payment of such distribution and in respect of which no adjustment
pursuant to paragraph (6) of this Section 12.4 has been made (the "combined cash
and tender amount") exceeds 10% of the product of the current market price per
share (determined as provided in paragraph (8) of this Section 12.4) of the
Common Stock on the date for the determination of holders of shares of Common
Stock entitled to receive such distribution times the number of shares of Common
Stock outstanding on such date (the "aggregate current market price"), then, and
in each such case, immediately after the close of business on such date for
determination, the Conversion Rate shall be adjusted so that the same shall
equal the rate determined by dividing the Conversion Rate in effect immediately
prior to the close of business on the date fixed for determination of the
stockholders entitled to receive such distribution by a fraction (i) the
numerator of which shall be equal to the current market price per share
(determined as provided in paragraph (8) of this Section) of the Common Stock on
the date fixed for such determination less an amount equal to the quotient of
(x) the excess of such combined cash and tender amount over such aggregate
current market price divided by (y) the number of shares of Common Stock
outstanding on such date for determination and (ii) the denominator of which
shall be equal to the current market price per share (determined as provided in
paragraph (8) of this Section 12.4) of the Common Stock on such date fixed for
determination.

         (6) In case a tender offer made by the Company or any Subsidiary for
all or any portion of the Common Stock shall expire and such tender offer (as
amended upon the expiration thereof) shall require the payment to stockholders
(based on the acceptance (up to any maximum specified in the terms of the tender
offer) of Purchased Shares (as defined below)) of an aggregate consideration
having a fair market value (as determined by the Board of Directors, whose
determination shall be conclusive and described in a Board Resolution) that
combined together with (I) the aggregate of the cash plus the fair market value
(as determined by the Board of Directors, whose determination shall be
conclusive and described in a Board Resolution), as of


                                      -74-

<PAGE>

the expiration of such tender offer, of consideration payable in respect of any
other tender offer by the Company or any Subsidiary for all or any portion of
the Common Stock expiring within the 365-day period preceding the expiration of
such tender offer and in respect of which no adjustment pursuant to this
paragraph (6) has been made and (II) the aggregate amount of any cash
distributions to all holders of the Common Stock within the 365-day period
preceding the expiration of such tender offer and in respect of which no
adjustment pursuant to paragraph (5) of this Section has been made (the
"combined tender and cash amount") exceeds ___% of the product of the current
market price per share of the Common Stock (determined as provided in paragraph
(8) of this Section 12.4) as of the last time (the "Expiration Time") tenders
could have been made pursuant to such tender offer (as it may be amended) times
the number of shares of Common Stock outstanding (including any tendered shares)
as of the Expiration Time, then, and in each such case, immediately prior to the
opening of business on the day after the date of the Expiration Time, the
Conversion Rate shall be adjusted so that the same shall equal the rate
determined by dividing the Conversion Rate immediately prior to close of
business on the date of the Expiration Time by a fraction (i) the numerator of
which shall be equal to (A) the product of (I) the current market price per
share of the Common Stock (determined as provided in paragraph (8) of this
Section 12.4) on the date of the Expiration Time multiplied by (II) the number
of shares of Common Stock outstanding (including any tendered shares) on the
Expiration Time less (B) the combined tender and cash amount, and (ii) the
denominator of which shall be equal to the product of (A) the current market
price per share of the Common Stock (determined as provided in paragraph (8) of
this Section 12.4) as of the Expiration Time multiplied by (B) the number of
shares of Common Stock outstanding (including any tendered shares) as of the
Expiration Time less the number of all shares validly tendered and not withdrawn
as of the Expiration Time (the shares deemed so accepted up to any such maximum,
being referred to as the "Purchased Shares").

         (7) The reclassification of Common Stock into securities other than
Common Stock (other than any reclassification upon a consolidation or merger to
which Section 12.11 applies) shall be deemed to involve (a) a distribution of
such securities other than Common Stock to all holders of Common Stock (and the
effective date of such reclassification shall be deemed to be "the date fixed
for the determination of stockholders entitled to receive such distribution" and
"the date fixed for such determination" within the meaning of paragraph (4) of
this Section), and (b) a subdivision or combination, as the case may be, of the
number of shares of Common Stock outstanding immediately prior to such
reclassification into the number of shares of Common Stock outstanding
immediately thereafter (and the effective date of such reclassification shall be
deemed to be "the day upon which such subdivision becomes effective" or "the day
upon which such combination becomes effective", as the case may be, and "the day
upon which such subdivision or combination becomes effective" within the meaning
of paragraph (3) of this Section 12.4).

         (8) For the purpose of any computation under paragraphs (2), (4), (5)
or (6) of this Section 12.4, the current market price per share of Common Stock
on any date shall be calculated by the Company and be deemed to be the average
of the daily Closing Prices Per Share for the five consecutive Trading Days
selected by the Company commencing not more than 10 Trading


                                      -75-

<PAGE>

Days before, and ending not later than the earlier of the day in question and
the day before the "ex" date with respect to the issuance or distribution
requiring such computation. For purposes of this paragraph, the term "'ex'
date", when used with respect to any issuance or distribution, means the first
date on which the Common Stock trades the regular way in the applicable
securities market or on the applicable securities exchange without the right to
receive such issuance or distribution.

         (9) No adjustment in the Conversion Rate shall be required unless such
adjustment (plus any adjustments not previously made by reason of this paragraph
(9)) would require an increase or decrease of at least one percent in such rate;
provided, however, that any adjustments which by reason of this paragraph (9)
are not required to be made shall be carried forward and taken into account in
any subsequent adjustment. All calculations under this Article shall be made to
the nearest cent or to the nearest one-hundredth of a share, as the case may be.

         (10) The Company may in its sole discretion make such increases in the
Conversion Rate, for the remaining term of the Securities or any shorter term,
in addition to those required by paragraphs (1), (2), (3), (4), (5) and (6) of
this Section 12.4, as it considers to be advisable in order to avoid or diminish
any income tax liability to any holders of shares of Common Stock resulting from
any dividend or distribution of stock or issuance of rights or warrants to
purchase or subscribe for stock or from any event treated as such for income tax
purposes. The Company shall have the power to resolve any ambiguity or correct
any error in this paragraph (10) and its actions in so doing shall, absent
manifest error, be final and conclusive.

         (11) Notwithstanding the foregoing provisions of this Section, no
adjustment of the Conversion Rate shall be required to be made (a) upon the
issuance of shares of Common Stock pursuant to any present or future plan for
the reinvestment of dividends or (b) because of a tender or exchange offer of
the character described in Rule 13e-4(h)(5) under the Exchange Act or any
successor rule thereto.

         (12) To the extent permitted by applicable law, the Company from time
to time may increase the Conversion Rate by any amount for any period of time if
the period is at least twenty (20) days and the Board of Directors shall have
made a determination that such increase would be in the best interests of the
Company, which determination shall be conclusive; provided, however, that no
such increase shall be taken into account for purposes of determining whether
the Closing Price Per Share of the Common Stock equals or exceeds ____% of the
Conversion Price in connection with an event which would otherwise be a Change
of Control pursuant to Section 14.4. Whenever the Conversion Rate is increased
pursuant to the preceding sentence, the Company shall give notice of the
increase to the Holders in the manner provided in Section 1.6 at least fifteen
(15) days prior to the date the increased Conversion Rate takes effect, and such
notice shall state the increased Conversion Rate and the period during which it
will be in effect.

         SECTION 12.5  NOTICE OF ADJUSTMENTS OF CONVERSION RATE.

         Whenever the Conversion Rate is adjusted as herein provided:


                                      -76-

<PAGE>

         (1) the Company shall compute the adjusted Conversion Rate in
accordance with Section 12.4 and shall prepare a certificate signed by the Chief
Financial Officer of the Company setting forth the adjusted Conversion Rate and
showing in reasonable detail the facts upon which such adjustment is based, and
such certificate shall promptly be filed with the Trustee and with each
Conversion Agent; and

         (2) upon each such adjustment, a notice stating that the Conversion
Rate has been adjusted and setting forth the adjusted Conversion Rate shall be
required, and as soon as practicable after it is required, such notice shall be
provided by the Company to all Holders in accordance with Section 1.6.

         Neither the Trustee nor any Conversion Agent shall be under any duty or
responsibility with respect to any such certificate or the information and
calculations contained therein, except to exhibit the same to any Holder
desiring inspection thereof at its office during normal business hours, and
shall not be deemed to have knowledge of any adjustment in the Conversion Rate
unless and until a Responsible Officer of the Trustee shall have received such a
certificate. Until a Responsible Officer of the Trustee receives such a
certificate, the Trustee and each Conversion Agent may assume without inquiry
that the last Conversion Rate of which the Trustee has knowledge of remains in
effect.

         SECTION 12.6  NOTICE OF CERTAIN CORPORATE ACTION.

         In case:

         (1) the Company shall declare a dividend (or any other distribution) on
its Common Stock payable (i) otherwise than exclusively in cash or (ii)
exclusively in cash in an amount that would require any adjustment pursuant to
Section 12.4; or

         (2) the Company shall authorize the granting to all or substantially
all of the holders of its Common Stock of rights, options or warrants to
subscribe for or purchase any shares of capital stock of any class or of any
other rights; or

         (3) of any reclassification of the Common Stock, or of any
consolidation, merger or share exchange to which the Company is a party and for
which approval of any stockholders of the Company is required, or of the
conveyance, sale, transfer or lease of all or substantially all of the assets of
the Company; or

         (4) of the voluntary or involuntary dissolution, liquidation or winding
up of the Company; then the Company shall cause to be filed at each office or
agency maintained for the purpose of conversion of Securities pursuant to
Section 10.2, and shall cause to be provided to all Holders in accordance with
Section 1.6, at least 20 days (or 10 days in any case specified in clause (1) or
(2) above) prior to the applicable record or effective date hereinafter
specified, a notice stating (x) the date on which a record is to be taken for
the purpose of such dividend,


                                      -77-

<PAGE>

distribution, rights, options or warrants, or, if a record is not to be taken,
the date as of which the holders of Common Stock of record to be entitled to
such dividend, distribution, rights, options or warrants are to be determined or
(y) the date on which such reclassification, consolidation, merger, conveyance,
transfer, sale, lease, dissolution, liquidation or winding up is expected to
become effective, and the date as of which it is expected that holders of Common
Stock of record shall be entitled to exchange their shares of Common Stock for
securities, cash or other property deliverable upon such reclassification,
consolidation, merger, conveyance, transfer, sale, lease, dissolution,
liquidation or winding up. Neither the failure to give such notice or the notice
referred to in the following paragraph nor any defect therein shall affect the
legality or validity of the proceedings described in clauses (1) through (4) of
this Section 12.6. If at the time the Trustee shall not be the Conversion Agent,
a copy of such notice shall also forthwith be filed by the Company with the
Trustee. The Company shall cause to be filed at each office or agency maintained
for the purpose of conversion of Securities pursuant to Section 10.2, and shall
cause to be provided to all Holders in accordance with Section 1.6, notice of
any tender offer by the Company or any Subsidiary for all or any portion of the
Common Stock at or about the time that such notice of tender offer is provided
to the public generally.

         SECTION 12.7  COMPANY TO RESERVE COMMON STOCK.

         The Company shall at all times reserve and keep available, free from
preemptive rights, out of its authorized but unissued Common Stock, for the
purpose of effecting the conversion of Securities, the full number of shares of
Common Stock then issuable upon the conversion of all Outstanding Securities.

         SECTION 12.8  TAXES ON CONVERSIONS.

         Except as provided in the next sentence, the Company will pay any and
all taxes and duties that may be payable in respect of the issue or delivery of
shares of Common Stock on conversion of Securities pursuant hereto. The Company
shall not, however, be required to pay any tax or duty which may be payable in
respect of any transfer involved in the issue and delivery of shares of Common
Stock in a name other than that of the Holder of the Security or Securities to
be converted, and no such issue or delivery shall be made unless and until the
Person requesting such issue has paid to the Company the amount of any such tax
or duty, or has established to the satisfaction of the Company that such tax or
duty has been paid.

         SECTION 12.9  COVENANT AS TO COMMON STOCK.

         The Company agrees that all shares of Common Stock which may be
delivered upon conversion of Securities, upon such delivery, will have been duly
authorized and validly issued and will be fully paid and nonassessable and,
except as provided in Section 12.8, the Company will pay all taxes, liens and
charges with respect to the issue thereof.


                                      -78-

<PAGE>

         SECTION 12.10  CANCELLATION OF CONVERTED SECURITIES.

         All Securities delivered for conversion shall be delivered to the
Trustee or its agent to be canceled by or at the direction of the Trustee, which
shall dispose of the same as provided in Section 3.9.

         SECTION 12.11  PROVISION IN CASE OF CONSOLIDATION, MERGER OR SALE OF
ASSETS.

         In case of any consolidation or merger of the Company with or into any
other Person, any merger of another Person with or into the Company (other than
a merger which does not result in any reclassification, conversion, exchange or
cancellation of outstanding shares of Common Stock of the Company) or any
conveyance, sale, transfer or lease of all or substantially all of the assets of
the Company, the Person formed by such consolidation or resulting from such
merger or which acquires such assets, as the case may be, shall execute and
deliver to the Trustee a supplemental indenture providing that the Holder of
each Security then Outstanding shall have the right thereafter, during the
period such Security shall be convertible as specified in Section 12.1, to
convert such Security only into the kind and amount of securities, cash and
other property receivable upon such consolidation, merger, conveyance, sale,
transfer or lease by a holder of the number of shares of Common Stock of the
Company into which such Security might have been converted immediately prior to
such consolidation, merger, conveyance, sale, transfer or lease, assuming such
holder of Common Stock of the Company (i) is not (A) a Person with which the
Company consolidated or merged with or into or which merged into or with the
Company or to which such conveyance, sale, transfer or lease was made, as the
case may be (a "Constituent Person"), or (B) an Affiliate of a Constituent
Person and (ii) failed to exercise his rights of election, if any, as to the
kind or amount of securities, cash and other property receivable upon such
consolidation, merger, conveyance, sale, transfer or lease (provided that if the
kind or amount of securities, cash and other property receivable upon such
consolidation, merger, conveyance, sale, transfer, or lease is not the same for
each share of Common Stock of the Company held immediately prior to such
consolidation, merger, conveyance, sale, transfer or lease by others than a
Constituent Person or an Affiliate thereof and in respect of which such rights
of election shall not have been exercised ("Non-electing Share"), then for the
purpose of this Section 12.11 the kind and amount of securities, cash and other
property receivable upon such consolidation, merger, conveyance, sale, transfer
or lease by the holders of each Non-electing Share shall be deemed to be the
kind and amount so receivable per share by a plurality of the Non-electing
Shares). Such supplemental indenture shall provide for adjustments which, for
events subsequent to the effective date of such supplemental indenture, shall be
as nearly equivalent as may be practicable to the adjustments provided for in
this Article. The above provisions of this Section 12.11 shall similarly apply
to successive consolidations, mergers, conveyances, sales, transfers or leases.
Notice of the execution of such a supplemental indenture shall be given by the
Company to the Holder of each Security as provided in Section 1.6 promptly upon
such execution.

         Neither the Trustee nor any Conversion Agent shall be under any
responsibility to determine the correctness of any provisions contained in any
such supplemental indenture relating either to the kind or amount of shares of
stock or other securities or property or cash


                                      -79-

<PAGE>

receivable by Holders upon the conversion of their Securities after any such
consolidation, merger, conveyance, transfer, sale or lease or to any such
adjustment, but may accept as conclusive evidence of the correctness of any such
provisions, and shall be protected in relying upon, an Officers' Certificate or
Opinion of Counsel with respect thereto, which the Company shall cause to be
furnished to the Trustee upon request.

         SECTION 12.12  RIGHTS ISSUED IN RESPECT OF COMMON STOCK.

         Rights, options or warrants distributed by the Company to all holders
of Common Stock entitling the holders thereof to subscribe for or purchase
shares of the Company's capital stock (either initially or under certain
circumstances), which rights, options or warrants, until the occurrence of a
specified event or events ("Trigger Event"):

         (i)      are deemed to be transferred with such shares of Common Stock,

         (ii)     are not exercisable, and

         (iii)    are also issued in respect of future issuances of Common Stock

shall not be deemed distributed for purposes of Section 12.4(2) until the
occurrence of the earliest Trigger Event. If such right, option or warrant is
subject to subsequent events, upon the occurrence of which such right, option or
warrant shall become exercisable to purchase different securities, evidences of
indebtedness or other assets or entitle the holder to purchase a different
number or amount of the foregoing or to purchase any of the foregoing at a
different purchase price, then the occurrence of each such event shall be deemed
to be the date of issuance and record date with respect to a new right, option
or warrant (and a termination or expiration of the existing right, option or
warrant without exercise by the holder thereof). In addition, in the event of
any distribution (or deemed distribution) of rights, options or warrants, or any
Trigger Event or other event (of the type described in the preceding sentence)
with respect thereto, that shall have resulted in an adjustment to the
Conversion Rate under Section 12.4(2), (1) in the case of any such rights,
options or warrants which shall all have been redeemed or repurchased without
exercise by any holders thereof, the Conversion Rate shall be readjusted upon
such final redemption or repurchase to give effect to such distribution or
Trigger Event, as the case may be, as though it were a cash distribution, equal
to the per share redemption or repurchase price received by a holder of Common
Stock with respect to such rights, options or warrants (assuming such holder had
retained such rights, options or warrants), made to all holders of Common Stock
as of the date of such redemption or repurchase, and (2) in the case of any such
rights, options or warrants all of which shall have expired without exercise by
any holder thereof, the Conversion Price shall be readjusted as if such issuance
had not occurred.


                                      -80-

<PAGE>

         SECTION 12.13  RESPONSIBILITY OF TRUSTEE FOR CONVERSION PROVISIONS.

         The Trustee, subject to the provisions of Section 6.1, and any
Conversion Agent shall not at any time be under any duty or responsibility to
any Holder to determine whether any facts exist which may require any adjustment
of the Conversion Rate, or with respect to the nature or extent of any such
adjustment when made, or with respect to the method employed, or herein or in
any supplemental indenture provided to be employed, in making the same, or
whether a supplemental indenture need be entered into. Neither the Trustee,
subject to the provisions of Section 6.1, nor any Conversion Agent shall be
accountable with respect to the validity or value (or the kind or amount) of any
Common Stock, or of any other securities or property or cash, which may at any
time be issued or delivered upon the conversion of any Security; and it or they
do not make any representation with respect thereto. Neither the Trustee,
subject to the provisions of Section 6.1, nor any Conversion Agent shall be
responsible for any failure of the Company to make or calculate any cash payment
or to issue, transfer or deliver any shares of Common Stock or share
certificates or other securities or property or cash upon the surrender of any
Security for the purpose of conversion; and the Trustee, subject to the
provisions of Section 6.1, and any Conversion Agent shall not be responsible for
any failure of the Company to comply with any of the covenants of the Company
contained in this Article.](68)


----------
         (68) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -81-

<PAGE>

                                  ARTICLE XIII

                     REPURCHASE OF SECURITIES AT THE OPTION
                     OF THE HOLDER UPON A CHANGE IN CONTROL

         SECTION 13.1 RIGHT TO REQUIRE REPURCHASE.

         In the event that a Change in Control (as hereinafter defined) shall
occur, then each Holder shall have the right, at the Holder's option, but
subject to the provisions of Section 13.2, to require the Company to repurchase,
and upon the exercise of such right the Company shall repurchase, all of such
Holder's Securities not theretofore called for redemption, or any portion of the
principal amount thereof that an integral multiple of U.S. $1,000 (provided that
no single Security may be repurchased in part unless the portion of the
principal amount of such Security to be Outstanding after such repurchase is
equal to an integral multiple of U.S. $1,000), on the date (the "Repurchase
Date") that is 45 days after the date of the Company Notice (as defined in
Section 13.3) at a purchase price equal to _____% of the principal amount of the
Securities to be repurchased plus interest accrued to the Repurchase Date (the
"Repurchase Price"); provided, however, that installments of interest on
Securities whose Stated Maturity is on or prior to the Repurchase Date shall be
payable to the Holders of such Securities, or one or more Predecessor
Securities, registered as such on the relevant Record Date according to their
terms and the provisions of Section 3.7. Such right to require the repurchase of
the Securities shall not continue after a discharge of the Company from its
obligations with respect to the Securities in accordance with Article IV, unless
a Change in Control shall have occurred prior to such discharge. At the option
of the Company, the Repurchase Price may be paid in cash or, subject to the
fulfillment by the Company of the conditions set forth Section 13.2, by delivery
of shares of Common Stock having a fair market value equal to the Repurchase
Price. Whenever in this Indenture (including Sections 2.2, 3.1, 5.1(1) and 5.8)
there is a reference, in any context, to the principal of any Security as of any
time, such reference shall be deemed to include reference to the Repurchase
Price payable in respect of such Security to the extent that such Repurchase
Price is, was or would be so payable at such time, and express mention of the
Repurchase Price in any provision of this Indenture shall not be construed as
excluding the Repurchase Price in those provisions of this Indenture when such
express mention is not made; provided, however, that for the purposes of Article
XIII such reference shall be deemed to include reference to the Repurchase Price
only to the extent the Repurchase Price is payable in cash.

         SECTION 13.2 CONDITIONS TO THE COMPANY'S ELECTION TO PAY THE REPURCHASE
PRICE OR THE MAKE-WHOLE PAYMENT IN COMMON STOCK.

         The Company may elect to pay the Repurchase Price by delivery of shares
of Common Stock pursuant to Section 13.1, and the Company may elect to pay the
Make-Whole Payment by delivery of shares of Common Stock pursuant to Section
2.2, if and only if the following conditions shall have been satisfied:


                                      -82-

<PAGE>

         (1) The shares of Common Stock deliverable in payment of the Repurchase
Price or Make-Whole Payment, as the case may be, shall have a fair market value
as of the Repurchase Date or the Redemption Date, as the case may be, of not
less than the Repurchase Price or Make-Whole Payment, as the case may be. For
purposes of Section 13.1 and this Section 13.2, the fair market value of shares
of Common Stock shall be determined by the Company and shall be equal to ____%
of the average of the Closing Price Per Share for the five consecutive Trading
Days immediately preceding and including the third Trading Day prior to the
Repurchase Date or the Redemption Date, as the case may be;

         (2) The Repurchase Price or Make-Whole Payment, as the case may be,
shall be paid only in cash in the event any shares of Common Stock to be issued
upon repurchase or redemption, as the case may be, of Securities hereunder (i)
require registration under any federal securities law before such shares may be
freely transferable without being subject to any transfer restrictions under the
Securities Act upon repurchase and if such registration is not completed or does
not become effective prior to the Repurchase Date or the Redemption Date, as the
case may be, and/or (ii) require registration with or approval of any
governmental authority under any state law or any other federal law before such
shares may be validly issued or delivered upon repurchase or redemption, as the
case may be, and if such registration is not completed or does not become
effective or such approval is not obtained prior to the Repurchase Date or the
Redemption Date, as the case may be;

         (3) Payment of the Repurchase Price or Make-Whole Payment, as the case
may be, may not be made in Common Stock unless such stock is, or shall have
been, approved for quotation on the Nasdaq National Market or listed on a
national securities exchange, in either case, prior to the Repurchase Date or
the Redemption Date, as the case may be; and

         (4) All shares of Common Stock which may be issued upon repurchase or
redemption, as the case may be, of Securities will be issued out of the
Company's authorized but unissued Common Stock and, will upon issue, be duly and
validly issued and fully paid and non-assessable and free of any preemptive
rights or rights of first refusal.

         If all of the conditions set forth in this Section 13.2 are not
satisfied in accordance with the terms thereof, the Repurchase Price or
Make-Whole Payment, as the case may be, shall be paid by the Company only in
cash.

         SECTION 13.3  NOTICES; METHOD OF EXERCISING REPURCHASE RIGHT, ETC.

         (1) Unless the Company shall have theretofore called for redemption all
of the Outstanding Securities, on or before the 30th day after the occurrence of
a Change in Control, the Company or, at the request and expense of the Company
on or before the 30th day after such occurrence, the Trustee, shall give to all
Holders, in the manner provided in Section 1.6, notice (the "Company Notice") of
the occurrence of the Change of Control and of the repurchase right set forth
herein arising as a result thereof. The Company shall also deliver a copy of
such notice


                                      -83-

<PAGE>

of a repurchase right to the Trustee and notify one or more
nationally-recognized reporting institutions such as Bloomberg of the Change in
Control and repurchase right.

         Each notice of a repurchase right shall state:

                  (i)      the Repurchase Date,

                  (ii)     the date by which the repurchase right must be
         exercised,

                  (iii) the Repurchase Price, and whether the Repurchase Price
         shall be paid by the Company in cash or by delivery of shares of Common
         Stock,

                  (iv) a description of the procedure which a Holder must follow
         to exercise a repurchase right, and the place or places where such
         Securities are to be surrendered for payment of the Repurchase Price
         and accrued interest, if any to the Repurchase Date,

                  (v) that on the Repurchase Date the Repurchase Price, and
         accrued interest, if any to the Repurchase Date, will become due and
         payable upon each such Security designated by the Holder to be
         repurchased, and that interest thereon shall cease to accrue on and
         after said date,

                  [(vi) the Conversion Rate then in effect, the date on which
         the right to convert the principal amount of the Securities to be
         repurchased will terminate and the place or places where such
         Securities may be surrendered for conversion,](69) and

                  (vii) the place or places that the Notice of Election of
         Holder to Require Repurchase as specified in Section 2.2 shall be
         delivered.

         No failure of the Company to give the foregoing notices or defect
therein shall limit any Holder's right to exercise a repurchase right or affect
the validity of the proceedings for the repurchase of Securities.

         If any of the foregoing provisions or other provisions of this Article
XIV are inconsistent with applicable law, such law shall govern.

         (2) To exercise a repurchase right, a Holder shall deliver to the
Trustee on or before the 30th day after the date of the Company Notice (i)
irrevocable written notice of the Holder's exercise of such right, which notice
shall set forth the name of the Holder, the principal amount of the Securities
to be repurchased (and, if any Security is to repurchased in part, the serial
number thereof, the portion of the principal amount thereof to be repurchased
and the name of the Person in which the portion thereof to remain Outstanding
after such repurchase is to be


----------
         (69) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -84-

<PAGE>

registered) and a statement that an election to exercise the repurchase right is
being made thereby, and, in the event that the Repurchase Price shall be paid in
shares of Common Stock, the name or names (with addresses) in which the
certificate or certificates for shares of Common Stock shall be issued, and (ii)
the Securities with respect to which the repurchase right is being exercised.
Such written notice shall be irrevocable[, except that the right of the Holder
to convert the Securities with respect to which the repurchase right is being
exercised shall continue until the close of business on the Business Day
immediately preceding the Repurchase Date](70).

         (3) In the event that a repurchase right shall be exercised in
accordance with the terms hereof, the Company shall pay or cause to be paid to
the Trustee the Repurchase Price in cash or shares of Common Stock, as provided
above, for payment to the Holder on the Repurchase Date or, if shares of Common
Stock are to be paid, as promptly after the Repurchase Date as practicable,
together with accrued and unpaid interest to the Repurchase Date payable with
respect to the Securities as to which the repurchase right has been exercised;
provided, however, that installments of interest that mature on or prior to the
Repurchase Date shall be payable in cash to the Holders of such Securities, or
one or more Predecessor Securities, registered as such at the close of business
on the relevant Regular Record Date.

         (4) If any Security (or portion thereof) surrendered for repurchase
shall not be so paid on the Repurchase Date, the principal amount of such
Security (or portion thereof, as the case may be) shall, until paid, bear
interest to the extent permitted by applicable law from the Repurchase Date at
the rate of _____% per annum[, and each Security shall remain convertible into
Common Stock until the principal of such Security (or portion thereof, as the
case may be) shall have been paid or duly provided for](71).

         (5) Any Security which is to be repurchased only in part shall be
surrendered to the Trustee (with, if the Company or the Trustee so requires, due
endorsement by, or a written instrument of transfer in form satisfactory to the
Company and the Trustee duly executed by, the Holder thereof or his attorney
duly authorized in writing), and the Company shall execute, and the Trustee
shall authenticate and make available for delivery to the Holder of such
Security without service charge, a new Security or Securities, containing
identical terms and conditions, each in an authorized denomination in aggregate
principal amount equal to and in exchange for the unrepurchased portion of the
principal of the Security so surrendered.

         (6) Any issuance of shares of Common Stock in respect of the Repurchase
Price shall be deemed to have been effected immediately prior to the close of
business on the Repurchase Date and the Person or Persons in whose name or names
any certificate or certificates for shares of Common Stock shall be issuable
upon such repurchase shall be deemed to have become on the Repurchase Date the
holder or holders of record of the shares represented thereby; provided,
however, that any surrender for repurchase on a date when the stock transfer
books of the


----------
         (70) INSERT IF SECURITIES ARE CONVERTIBLE

         (71) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -85-

<PAGE>

Company shall be closed shall constitute the Person or Persons in whose name or
names the certificate or certificates for such shares are to be issued as the
record holder or holders thereof for all purposes at the opening of business on
the next succeeding day on which such stock transfer books are open. No payment
or adjustment shall be made for dividends or distributions on any Common Stock
issued upon repurchase of any Security declared prior to the Repurchase Date.

         (7) No fractions of shares shall be issued upon repurchase of
Securities. If more than one Security shall be repurchased from the same Holder
and the Repurchase Price shall be payable in shares of Common Stock, the number
of full shares which shall be issuable upon such repurchase shall be computed on
the basis of the aggregate principal amount of the Securities so repurchased.
Instead of any fractional share of Common Stock which would otherwise be
issuable on the repurchase of any Security or Securities, the Company will
deliver to the applicable Holder its check for the current market value of such
fractional share. The current market value of a fraction of a share is
determined by multiplying the current market price of a full share by the
fraction, and rounding the result to the nearest cent. For purposes of this
Section, the current market price of a share of Common Stock is the Closing
Price Per Share on the Trading Day immediately preceding the Repurchase Date.

         (8) Any issuance and delivery of certificates for shares of Common
Stock on repurchase of Securities shall be made without charge to the Holder
being repurchased for such certificates or for any tax or duty in respect of the
issuance or delivery of such certificates or the securities represented thereby;
provided, however, that the Company shall not be required to pay any tax or duty
which may be payable in respect of (i) income of the Holder or (ii) any transfer
involved in the issuance or delivery of certificates for shares of Common Stock
in a name other than that of the Holder of the Securities being repurchased, and
no such issuance or delivery shall be made unless and until the Person
requesting such issuance or delivery has paid to the Company the amount of any
such tax or duty or has established, to the reasonable satisfaction of the
Company, that such tax or duty has been paid.

         (9) All Securities delivered for repurchase shall be delivered to the
Trustee to be canceled at the direction of the Trustee, which shall dispose of
the same as provided in Section 3.9.

         SECTION 13.4  CERTAIN DEFINITIONS.

         For purposes of this Article XIII,

         (1) the term "beneficial owner" shall be determined in accordance with
Rule 13d-3, as in effect on the date of the original execution of this
Indenture, promulgated by the Commission pursuant to the Exchange Act;

         (2) a "Change in Control" shall be deemed to have occurred at the time,
after the original issuance of the Securities, of:


                                      -86-

<PAGE>

                  (i) the acquisition by any Person of beneficial ownership,
         directly or indirectly, through a purchase, merger or other acquisition
         transaction or series of transactions, of shares of capital stock of
         the Company entitling such person to exercise 50% or more of the total
         voting power of all shares of capital stock of the Company entitled to
         vote generally in the elections of directors, other than any such
         acquisition by the Company, any subsidiary of the Company or any
         employee benefit plan of the Company; or

                  (ii) any consolidation of the Company with, or merger of the
         Company into, any other Person, any merger of another Person into the
         Company, or any conveyance, sale, transfer or lease of all or
         substantially all of the assets of the Company to another Person (other
         than (a) any such transaction [(X)](72) which does not result in any
         reclassification, conversion, exchange or cancellation of outstanding
         shares of capital stock of the Company and (y) pursuant to which the
         holders of the Common Stock immediately prior to such transaction have
         the entitlement to exercise, directly or indirectly, 50% or more of the
         total voting power of all shares of capital stock entitled to vote
         generally in the election of directors of the continuing or surviving
         Person immediately after such transaction and (b) any merger which is
         effected solely to change the jurisdiction of incorporation of the
         Company and results in a reclassification, conversion or exchange of
         outstanding shares of Common Stock into solely shares of common stock);
         provided, however, that a Change in Control shall not be deemed to have
         occurred if (x) the Closing Price Per Share on any five Trading Days
         within the period of 10 consecutive Trading Days ending immediately
         after the later of the date of the Change in Control or the date of the
         public announcement of the Change in Control (in the case of a Change
         in Control under clause (i) above) or the period of 10 consecutive
         Trading Days ending immediately before the Change in Control (in the
         case of a Change in Control under clause (ii) above) shall equal or
         exceed _______________ [or (y) all of the consideration (excluding cash
         payments for fractional shares and cash payments made pursuant to
         dissenters' appraisal rights) in a merger or consolidation otherwise
         constituting a Change of Control under clause (i) and/or clause (ii)
         above consists of shares of common stock traded on a national
         securities exchange or quoted on the Nasdaq National Market (or will be
         so traded or quoted immediately following such merger or consolidation)
         and as a result of such merger or consolidation the notes become
         convertible into such common stock](73).

         [(3) the term "Conversion Price" shall equal U.S. $1,000 divided by the
Conversion Rate (rounded to the nearest cent)(74); and


----------
         (72) INSERT IF SECURITIES ARE CONVERTIBLE

         (73) INSERT IF SECURITIES ARE CONVERTIBLE

         (74) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -87-

<PAGE>

         (4) for purposes of Section 13.4(2)(i), the term "Person" shall include
any syndicate or group which would be deemed to be a "Person" under Section
13(d)(3) of the Exchange Act, as in effect on the date of the original execution
of this Indenture.

         [SECTION 13.5  CONSOLIDATION, MERGER, ETC.

         In the case of any merger, consolidation, conveyance, sale, transfer or
lease of all or substantially all of the assets of the Company to which Section
12.11 applies, in which the Common Stock of the Company is changed or exchanged
as a result into the right to receive shares of stock and other securities or
property or assets (including cash) which includes shares of Common Stock of the
Company or common stock of another Person that are, or upon issuance will be,
traded on a United States national securities exchange or approved for trading
on an established automated over-the-counter trading market in the United States
and such shares constitute at the time such change or exchange becomes effective
in excess of 50% of the aggregate fair market value of such shares of stock and
other securities, property and assets (including cash) (as determined by the
Company, which determination shall be conclusive and binding), then the Person
formed by such consolidation or resulting from such merger or combination or
which acquires the properties or assets (including cash) of the Company, as the
case may be, shall execute and deliver to the Trustee a supplemental indenture
(which shall comply with the Trust Indenture Act as in force at the date of
execution of such supplemental indenture) modifying the provisions of this
Indenture relating to the right of Holders to cause the Company to repurchase
the Securities following a Change in Control, including without limitation the
applicable provisions of this Article XIII and the definitions of the Common
Stock and Change in Control, as appropriate, and such other related definitions
set forth herein as determined in good faith by the Company (which determination
shall be conclusive and binding), to make such provisions apply in the event of
a subsequent Change in Control to the common stock and the issuer thereof if
different from the Company and Common Stock of the Company (in lieu of the
Company and the Common Stock of the Company).](75)

                                   ARTICLE XIV

         HOLDERS LISTS AND REPORTS BY TRUSTEE AND COMPANY; NON-RECOURSE

         SECTION 14.1  COMPANY TO FURNISH TRUSTEE NAMES AND ADDRESSES OF
HOLDERS.

         The Company will furnish or cause to be furnished to the Trustee:


----------
         (75) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -88-

<PAGE>

         (1) semi-annually, not more than 15 days after the Regular Record Date,
a list, in such form as the Trustee may reasonably require, of the names and
addresses of the Holders as of such Regular Record Date, and

         (2) at such other times as the Trustee may reasonably request in
writing, within 30 days after the receipt by the Company of any such request, a
list of similar form and content as of a date not more than 15 days prior to the
time such list is furnished; excluding from any such list names and addresses
received by the Trustee acting in its capacity as Security Registrar.

         SECTION 14.2  PRESERVATION OF INFORMATION.

         (1) The Trustee shall preserve, in as current a form as is reasonably
practicable, the names and addresses of Holders contained in the most recent
list furnished to the Trustee as provided in Section 14.1 and the names and
addresses of Holders received by the Trustee in its capacity as Security
Registrar. The Trustee may destroy any list, if any, furnished to it as provided
in Section 14.1 upon receipt of a new list so furnished.

         (2) The rights of Holders to communicate with other Holders with
respect to their rights under this Indenture or under the Securities, and the
corresponding rights and duties of the Trustee, shall be as provided by the
Trust Indenture Act.

         (3) Every Holder, by receiving and holding the same, agrees with the
Company and the Trustee that neither the Company nor the Trustee nor any agent
of either of them shall be held accountable by reason of any disclosure of
information as to names and addresses of Holders made pursuant to the Trust
Indenture Act.

         SECTION 14.3  REPORTS BY TRUSTEE.

         (1) The Trustee shall transmit to Holders such reports concerning the
Trustee and its actions under this Indenture as may be required pursuant to the
Trust Indenture Act at the times and in the manner provided pursuant thereto.

         (2) A copy of each such report shall, at the time of such transmission
to Holders, be filed by the Trustee with each stock exchange upon which the
Securities are listed, with the Commission and with the Company. The Company
will notify the Trustee when the Securities are listed on any stock exchange.

         SECTION 14.4  REPORTS BY COMPANY.

         The Company shall file with the Trustee and the Commission, and
transmit to Holders, such information, documents and other reports, and such
summaries thereof, as may be required pursuant to the Trust Indenture Act at the
times and in the manner provided pursuant to the Trust Indenture Act; provided
that any such information, documents or reports required to be filed with


                                      -89-

<PAGE>

the Commission pursuant to Section 13 or 15(d) of the Exchange Act shall be
filed with the Trustee within 15 days after the same is so required to be filed
with the Commission.

                                   ARTICLE XV

         IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS AND DIRECTORS

         SECTION 15.1 INDENTURE AND SECURITIES SOLELY CORPORATE OBLIGATIONS.

         No recourse for the payment of the principal of or premium (including
any Make-Whole Payment), if any, or interest on any Security and no recourse
under or upon any obligation, covenant or agreement of the Company in this
Indenture or in any supplemental indenture or in any Security, or because of the
creation of any indebtedness represented thereby, shall be had against any
incorporator, stockholder, employee, agent, officer, or director or subsidiary,
as such, past, present or future, of the Company or of any successor
corporation, whether by virtue of any constitution, statute or rule of law, or
by the enforcement of any assessment or penalty or otherwise; it being expressly
understood that all such liability is hereby waived and released as a condition
of, and as a consideration for, the execution of this Indenture and the issue of
the Securities.

         This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.

         IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed all as of the day and year first above written.

SONUS NETWORKS, INC.

By:___________________________
Name:
Title:

_______________________________,
as Trustee

By:___________________________
Name:
Title:


                                      -90-



<PAGE>


                                                                   Exhibit 4.3

                            -------------------------


                              SONUS NETWORKS, INC.

                                     ISSUER

                                       TO

                           [-------------------------]

                                     TRUSTEE


                            -------------------------


                                    INDENTURE


                        Dated as of              ,
                                    -------------  -----


                            -------------------------


                          SUBORDINATED DEBT SECURITIES


                            -------------------------







<PAGE>




                                TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                           PAGE
<S>                                                                        <C>
ARTICLE I DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION............1

  SECTION 1.1  Definitions ..................................................1
  SECTION 1.2  Compliance Certificates And Opinions.........................11
  SECTION 1.3  Form of Documents Delivered to the Trustee...................11
  SECTION 1.4  Acts of Holders .............................................12
  SECTION 1.5  Notices, Etc. to the Trustee and Company.....................14
  SECTION 1.6  Notice to Holders; Waiver....................................14
  SECTION 1.7  Effect of Headings and Table of Contents.....................15
  SECTION 1.8  Successors and Assigns.......................................15
  SECTION 1.9  Separability Clause..........................................15
  SECTION 1.10 Benefits of Indenture........................................15
  SECTION 1.11 Governing Law................................................15
  SECTION 1.12 Legal Holidays...............................................16
  SECTION 1.13 Conflict With Trust Indenture Act............................16

ARTICLE II SECURITY FORMS...................................................17

  SECTION 2.1  Form Generally...............................................17
  SECTION 2.2  Form of Security.............................................17
  SECTION 2.3  Form of Certificate of Authentication........................28
  SECTION 2.4  Form of Conversion Notice....................................29
  SECTION 2.5  Form of Assignment...........................................30

ARTICLE III THE SECURITIES..................................................31

  SECTION 3.1  Title and Terms..............................................31
  SECTION 3.2  Denominations................................................32
  SECTION 3.3  Execution, Authentication, Delivery and Dating...............32
  SECTION 3.4  Global Securities; Non-global Securities; Book-entry 
               Provisions...................................................32
  SECTION 3.5  Registration;
 Registration of Transfer and Exchange; 
               Restrictions on Transfer.....................................34
  SECTION 3.6  Mutilated, Destroyed, Lost or Stolen Securities..............35
  SECTION 3.7  Payment of Interest; Interest Rights Preserved...............36
  SECTION 3.8  Persons Deemed Owners........................................37
  SECTION 3.9  Cancellation.................................................38
  SECTION 3.10 Computation of Interest......................................38
  SECTION 3.11 CUSIP Numbers................................................38
</TABLE>



<PAGE>


<TABLE>
<S>                                                                         <C>
ARTICLE IV SATISFACTION AND DISCHARGE.......................................38

  SECTION 4.1  Satisfaction and Discharge of Indenture......................38
  SECTION 4.2  Application of Trust Money...................................39

ARTICLE V REMEDIES..........................................................40

  SECTION 5.1  Events of Default............................................40
  SECTION 5.2  Acceleration of Maturity; Rescission and Annulment...........42
  SECTION 5.3  Collection of Indebtedness and Suits for Enforcement 
                 by Trustee.................................................43
  SECTION 5.4  Trustee May File Proofs of Claim.............................43
  SECTION 5.5  Trustee May Enforce Claims Without Possession 
                 of Securities..............................................44
  SECTION 5.6  Application of Money Collected...............................44
  SECTION 5.7  Limitation on Suits..........................................45
  SECTION 5.8  Unconditional Right of Holders to Receive Principal, 
                 Premium and Interest and to Convert........................46
  SECTION 5.9  Restoration of Rights and Remedies...........................46
  SECTION 5.10 Rights and Remedies Cumulative...............................46
  SECTION 5.11 Delay or Omission Not Waiver.................................46
  SECTION 5.12 Control by Holders...........................................47
  SECTION 5.13 Waiver of Past Defaults......................................47
  SECTION 5.14 Undertaking for Costs........................................47
  SECTION 5.15 Waiver of Stay, Usury or Extension Laws......................48

ARTICLE VI THE TRUSTEE......................................................48

  SECTION 6.1  Certain Duties and Responsibilities..........................48
  SECTION 6.2  Notice of Defaults...........................................49
  SECTION 6.3  Certain Rights of Trustee....................................50
  SECTION 6.4  Not Responsible for Recitals or Issuance of Securities.......51
  SECTION 6.5  May Hold Securities, Act as Trustee under Other Indentures...51
  SECTION 6.6  Money Held in Trust..........................................51
  SECTION 6.7  Compensation and Reimbursement...............................51
  SECTION 6.8  Corporate Trustee Required; Eligibility......................52
  SECTION 6.9  Resignation and Removal; Appointment of Successor............52
  SECTION 6.10 Acceptance of Appointment by Successor.......................54
  SECTION 6.11 Merger, Conversion, Consolidation or Succession 
                  to Business...............................................54
  SECTION 6.12  Authenticating Agents.......................................54
  SECTION 6.13  Disqualification; Conflicting Interests.....................56
  SECTION 6.14  Preferential Collection of Claims Against Company...........56
</TABLE>

                                      -ii-


<PAGE>



<TABLE>
<S>                                                                         <C>
ARTICLE VII CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE............56

  SECTION 7.1  Company May Consolidate, Etc., Only on 
    Certain Terms...........................................................56
  SECTION 7.2  Successor Substituted........................................57

ARTICLE VIII SUPPLEMENTAL INDENTURES........................................57

  SECTION 8.1  Supplemental Indentures Without Consent of Holders...........57
  SECTION 8.2  Supplemental Indentures with Consent of Holders..............58
  SECTION 8.3  Execution of Supplemental Indentures.........................59
  SECTION 8.4  Effect of Supplemental Indentures............................60
  SECTION 8.5  Reference in Securities to Supplemental Indentures...........60
  SECTION 8.6  Notice of Supplemental Indentures............................60

ARTICLE IX MEETINGS OF HOLDERS..............................................60

  SECTION 9.1  Purposes for Which Meetings May Be Called....................60
  SECTION 9.2  Call, Notice and Place of Meetings...........................61
  SECTION 9.3  Persons Entitled to Vote at Meetings.........................61
  SECTION 9.4  Quorum; Action...............................................61
  SECTION 9.5  Determination of Voting Rights; Conduct and 
                 Adjournment of Meetings....................................62
  SECTION 9.6  Counting Votes and Recording Action of Meetings..............63

ARTICLE X COVENANTS.........................................................63

  SECTION 10.1  Payment of Principal, Premium and Interest..................63
  SECTION 10.2  Maintenance of Offices or Agencies..........................64
  SECTION 10.3  Money for Security Payments to Be Held in Trust.............64
  SECTION 10.4  Existence...................................................66
  SECTION 10.5  Payment of Taxes and Other Claims...........................66
  SECTION 10.6  Registration and Listing....................................66
  SECTION 10.7  Statement by Officers as to Default.........................67
  SECTION 10.8  Waiver of Certain Covenants.................................67

ARTICLE XI REDEMPTION OF SECURITIES.........................................67

  SECTION 11.1  Right of Redemption.........................................67
  SECTION 11.2  Applicability of Article....................................68
  SECTION 11.3  Election to Redeem; Notice to Trustee.......................68
  SECTION 11.4  Selection by Trustee of Securities to Be Redeemed...........68
  SECTION 11.5  Notice of Redemption........................................69
  SECTION 11.6  Deposit of Redemption Price.................................69
  SECTION 11.7  Securities Payable on Redemption Date.......................70
  SECTION 11.8  Conversion Arrangement on Call for Redemption...............71
</TABLE>


                                     -iii-


<PAGE>



<TABLE>
<S>                                                                         <C>
ARTICLE XII CONVERSION OF SECURITIES........................................72

  SECTION 12.1  Conversion Privilege and Conversion Rate....................72
  SECTION 12.2  Exercise of Conversion Privilege............................72
  SECTION 12.3  Fractions of Shares.........................................73
  SECTION 12.4  Adjustment of Conversion Rate...............................74
  SECTION 12.5  Notice of Adjustments of Conversion Rate....................78
  SECTION 12.6  Notice of Certain Corporate Action..........................79
  SECTION 12.7  Company to Reserve Common Stock.............................80
  SECTION 12.8  Taxes on Conversions........................................80
  SECTION 12.9  Covenant as to Common Stock.................................80
  SECTION 12.10 Cancellation of Converted Securities........................80
  SECTION 12.11 Provision in Case of Consolidation, Merger or 
                   Sale of Assets...........................................80
  SECTION 12.12 Rights Issued in respect of Common Stock....................81
  SECTION 12.13 Responsibility of Trustee for Conversion Provisions.........82

ARTICLE XIII SUBORDINATION OF SECURITIES....................................83

  SECTION 13.1  Securities Subordinate to Senior Debt.......................83
  SECTION 13.2  No Payment in Certain Circumstances, Payment over 
                  of Proceeds upon Dissolution, Etc.........................83
  SECTION 13.3  Prior Payment to Senior Debt upon Acceleration 
                  of Securities.............................................85
  SECTION 13.4  Payment Permitted If No Default.............................86
  SECTION 13.5  Subrogation to Rights of Holders of Senior Debt.............86
  SECTION 13.6  Provisions Solely to Define Relative Rights.................86
  SECTION 13.7  Trustee to Effectuate Subordination.........................87
  SECTION 13.8  No Waiver of Subordination Provisions.......................87
  SECTION 13.9  Notice to Trustee...........................................87
  SECTION 13.10 Reliance on Judicial Order or Certificate of 
                   Liquidating Agent........................................88
  SECTION 13.11 Trustee Not Fiduciary for Holders of Senior Debt............88
  SECTION 13.12 Reliance by Holders of Senior Debt on Subordination 
                   Provisions...............................................89
  SECTION 13.13 Rights of Trustee as Holder of Senior Debt; 
                   Preservation of Trustee's Rights.........................89
  SECTION 13.14 Article Applicable to Paying Agents.........................89
  SECTION 13.15 Certain Conversions and Repurchases Deemed Payment..........90

ARTICLE XIV REPURCHASE OF SECURITIES AT THE OPTION OF THE HOLDER
         UPON A CHANGE IN CONTROL...........................................91

  SECTION 14.1  Right to Require Repurchase.................................91
  SECTION 14.2  Conditions to the Company's Election to Pay the 
                   Repurchase Price or the Make-Whole Payment in 
                   Common Stock.............................................91
</TABLE>


                                      -iv-


<PAGE>



  SECTION 14.3  Notices; Method of Exercising Repurchase Right, Etc.........92
  SECTION 14.4  Certain Definitions.........................................95
  SECTION 14.5  Consolidation, Merger, Etc..................................97

ARTICLE XV HOLDERS LISTS AND REPORTS BY TRUSTEE AND COMPANY;
  NON-RECOURSE..............................................................97

  SECTION 15.1  Company to Furnish Trustee Names and Addresses of 
                  Holders...................................................97
  SECTION 15.2  Preservation of Information.................................98
  SECTION 15.3  Reports by Trustee..........................................98
  SECTION 15.4  Reports by Company..........................................98

ARTICLE XVI IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS
         AND DIRECTORS......................................................99

  SECTION 16.1  Indenture and Securities Solely Corporate Obligations.......99

                                      -v-


<PAGE>


<TABLE>
<CAPTION>
TRUST INDENTURE ACT SECTION                                                              INDENTURE SECTION

<S>                                                                                      <C>
Section     310    (a)(1)..............................................................  6.8
                   (a)(2)..............................................................  6.8
                   (a)(3)..............................................................  Not Applicable
                   (a)(4)..............................................................  Not Applicable
                   (b).................................................................  6.8, 6.9, 6.13
Section     311    (a).................................................................  6.14
                   (b).................................................................  6.14
Section     312    (a).................................................................  15.1, 15.2(1)
                   (b).................................................................  15.2(2)
                   (c).................................................................  15.2(3)
Section     313    (a).................................................................  15.3(1)
                   (b).................................................................  15.3(1)
                   (c).................................................................  15.3(1)
                   (d).................................................................  15.3(2)
Section     314    (a)(1)..............................................................  15.4
                   (a)(2)..............................................................  15.4
                   (a)(3)..............................................................  15.4
                   (a)(4)..............................................................  10.7
                   (b).................................................................  Not Applicable
                   (c)(1)..............................................................  1.2
                   (c)(2)..............................................................  1.2
                   (c)(3)..............................................................  Not Applicable
                   (d).................................................................  Not Applicable
                   (e).................................................................  1.2
Section     315    (a).................................................................  6.1(1), 6.3
                   (b).................................................................  6.2
                   (c).................................................................  6.1(2)
                   (d).................................................................  6.1(3)
                   (e).................................................................  5.14
Section     316    (a)(last sentence)..................................................  1.1 ("Outstanding")
                   (a)(1)(A)...........................................................  5.12
                   (a)(1)(B)...........................................................  5.13
                   (a)(2)..............................................................  Not Applicable
                   (b).................................................................  5.8
                   (c).................................................................  1.4
Section     317    (a)(1)..............................................................  5.3
                   (a)(2)..............................................................  5.4
                   (b).................................................................  10.3
Section     318    (a).................................................................  1.7
</TABLE>



                                      -vi-


<PAGE>



        INDENTURE, dated as of _________________________,____ between SONUS
NETWORKS, INC., a corporation duly organized and existing under the laws of the
State of Delaware, having its principal office at 5 Carlisle Road, Westford,
Massachusetts 01886 (herein called the "Company"), and _____________________, a
________________ corporation, as Trustee hereunder (herein called the
"Trustee").

                             RECITALS OF THE COMPANY

        The Company has duly authorized the creation of an issue of its ____%
[Convertible](1) Subordinated Notes due ______,_____ (herein called the
"Securities") of substantially the tenor and amount hereinafter set forth, and
to provide therefor the Company has duly authorized the execution and delivery
of this Indenture.

        All things necessary to make the Securities, when the Securities are
executed by the Company and authenticated and delivered hereunder, the valid
obligations of the Company, and to make this Indenture a valid agreement of the
Company, in accordance with their and its terms, have been done. [Further, all
things necessary to duly authorize the issuance of the Common Stock of the
Company issuable upon the conversion of the Securities, and to duly reserve for
issuance the number of shares of Common Stock issuable upon such conversion,
have been done.](2)

        NOW, THEREFORE, THIS INDENTURE WITNESSETH:

        For and in consideration of the premises and the purchase of the 
Securities by the Holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all Holders of the Securities, as follows:

                                    ARTICLE I

        DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

        SECTION 1.1 DEFINITIONS.

        For all purposes of this Indenture, except as otherwise expressly 
provided or unless the context otherwise requires:

        (1)  the terms  defined in this Article have the meanings assigned to 
them in this Article and include the plural as well as the singular;


----------
        (1) INSERT IF SECURITIES ARE CONVERTIBLE

        (2) INSERT IF SECURITIES ARE CONVERTIBLE



<PAGE>


        (2) all accounting terms not otherwise defined herein have the meanings
assigned to them in accordance with generally accepted accounting principles in
the United States, and, except as otherwise herein expressly provided, the term
"generally accepted accounting principles" with respect to any computation
required or permitted hereunder shall mean such accounting principles as are
generally accepted at the date of such computation; and

        (3) the words "herein", "hereof" and "hereunder" and other words of
similar import refer to this Indenture as a whole and not to any particular
Article, Section or other subdivision.

        "Act", when used with respect to any Holder, has the meaning specified
in Section 1.4.

        "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For the purposes of this definition,
"control", when used with respect to any specified Person, means the power to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

        "Agent Member" means any member of, or participant in, the Depositary.

        "Applicable Procedures" means, with respect to any transfer or 
transaction involving a Global Security or beneficial interest therein, the
rules and procedures of the Depositary for such Global Security, in each case to
the extent applicable to such transaction and as in effect from time to time.

         "Authenticating Agent" means any Person authorized pursuant to Section
6.12 to act on behalf of the Trustee to authenticate Securities.

         "Board of Directors" means either the board of directors of the Company
or any duly authorized committee of that board.

         "Board Resolution" means a resolution duly adopted by the Board of
Directors, a copy of which, certified by the Secretary or an Assistant Secretary
of the Company to have been duly adopted by the Board of Directors and to be in
full force and effect on the date of such certification, shall have been
delivered to the Trustee.

        "Business Day", when used with respect to any Place of Payment [or Place
of Conversion, as the case may be,](3) means each Monday, Tuesday, Wednesday,
Thursday and Friday which is not a day on which banking institutions in such
Place of Payment[, Place of Conversion](4) or other place, as the case may be,
are authorized or obligated by law or executive


----------

        (3) INSERT IF SECURITIES ARE CONVERTIBLE

        (4) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -2-

<PAGE>



order to close; provided, however, that a day on which banking institutions in
New York, New York are authorized or obligated by law or executive order to
close shall not be a Business Day for purposes of Section 13.9.

         "Change in Control" has the meaning specified in Section 14.4(2).

         "Closing Price Per Share" means, with respect to the Common Stock, for
any day, (i) the last reported bid price regular way on the Nasdaq National
Market or, (ii) if the Common Stock is not quoted on the Nasdaq National Market,
the last reported sale price regular way per share or, in case no such reported
sale takes place on such day, the average of the reported closing bid and asked
prices regular way, in either case, on the principal national securities
exchange on which the Common Stock is listed or admitted to trading, or (iii) if
the Common Stock is not quoted on the Nasdaq National Market or listed or
admitted to trading on any national securities exchange, the average of the
closing bid prices in the over-the-counter market as furnished by any New York
Stock Exchange member firm selected from time to time by the Company for that
purpose.

         "Code" has the meaning specified in Section 2.l.

         "Commission" means the United States Securities and Exchange
Commission, as from time to time constituted, created under the Exchange Act,
or, if at any time after the execution of this instrument such Commission is not
existing and performing the duties now assigned to it under the Trust Indenture
Act, then the body performing such duties at such time.

        "Common Stock" means the Common Stock, par value $0.001 per share, of
the Company authorized at the date of this instrument as originally executed.
[Subject to the provisions of Section 12.11,](5) shares issuable on
[conversion](6) or repurchase of Securities shall include only shares of Common
Stock or shares of any class or classes of common stock resulting from any
reclassification or reclassifications thereof[; provided, however, that if at
any time there shall be more than one such resulting class, the shares so
issuable on conversion of Securities shall include shares of all such classes,
and the shares of each such class then so issuable shall be substantially in the
proportion which the total number of shares of such class resulting from all
such reclassifications bears to the total number of shares of all such classes
resulting from all such reclassifications.](7)

        "common stock" includes any stock of any class of capital stock which
has no preference in respect of dividends or of amounts payable in the event of
any voluntary or involuntary

----------

        (5) INSERT IF SECURITIES ARE CONVERTIBLE

        (6) INSERT IF SECURITIES ARE CONVERTIBLE

        (7) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -3-

<PAGE>



liquidation, dissolution or winding up of the issuer thereof and which is not
subject to redemption by the issuer thereof.

         "Company" means the Person named as the "Company" in the first
paragraph of this instrument until a successor Person shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Company" shall mean such successor Person.

         "Company Notice" has the meaning specified in Section 14.3.

         "Company Request" or "Company Order" means a written request or order
signed in the name of the Company by its (i) Chairman of the Board, its Vice
Chairman of the Board, its Chief Executive Officer, its President, an Executive
Vice President or a Vice President, and by its (ii) principal financial officer,
Treasurer, an Assistant Treasurer, its Secretary or an Assistant Secretary, and
delivered to the Trustee.

         ["Conversion Agent" means any Person authorized by the Company to
convert Securities in accordance with Article XII. The Company has initially
appointed the Trustee as its Conversion Agent pursuant to Section 10.2 hereof.

         "Constituent Person" has the meaning specified in Section 12.11.]

         ["Conversion Price" has the meaning specified in Section 14.4(3).

         "Conversion Rate" has the meaning specified in Section 12.1.](9)

        "Corporate Trust Office" means the office of the Trustee at which at any
particular time its corporate trust business shall be principally administered
(which at the date of this Indenture is located at _______________, Attention:
_____________________________ .

        "corporation" means a corporation, company, association, joint-stock
company or business trust.

         "Defaulted Interest" has the meaning specified in Section 3.7.

         "Depositary" means, with respect to any Securities (including any
Global Securities), a clearing agency that is registered as such under the
Exchange Act and is designated by the Company to act as Depositary for such
Securities (or any successor securities clearing agency so registered).


----------

        (8) INSERT IF SECURITIES ARE CONVERTIBLE

        (9)  INSERT IF SECURITIES ARE CONVERTIBLE

                                      -4-


<PAGE>


        "Designated Senior Debt" means any particular Senior Debt in which the
instrument creating or evidencing the same or the assumption or guarantee
thereof (or related agreements or documents to which the Company is a party)
expressly provides that such Senior Debt shall be "Designated Senior Debt" for
purposes of this Indenture (provided that such instrument, agreement or other
document may place limitations and conditions on the right of such Senior Debt
to exercise the rights of Designated Senior Debt).

         "Dollar" or "U.S. $" means a dollar or other equivalent unit in such
coin or currency of the United States as at the time shall be legal tender for
the payment of public and private debts.

        "DTC" means The Depository Trust Company, a New York corporation.

        "Event of Default" has the meaning specified in Section 5.1.

        "Exchange Act" means the United States Securities Exchange Act of 1934
(or any successor statute), as amended from time to time.

        "Global Security" means a Security that is registered in the Security
Register in the name of a Depositary or a nominee thereof.

        "Holder" means the Person in whose name the Security is registered in
the Security Register.

        "Indenture" means this instrument as originally executed and as it may
from time to time be supplemented or amended by one or more indentures
supplemental hereto entered into pursuant to the applicable provisions hereof,
including, for all purposes of this instrument and any such supplemental
indenture, the provisions of the Trust Indenture Act that are deemed to be a
part of and govern this instrument and any such supplemental indenture,
respectively.

        "Interest Payment Date" means the Stated Maturity of an installment of
interest on the Securities.

        "Issue Date" means ____________, ______.

        "Make-Whole Payment" has the meaning specified in Section 2.2.

        "Maturity", when used with respect to any Security, means the date on
which the principal of such Security becomes due and payable as therein or
herein provided, whether at the Stated Maturity or by declaration of
acceleration, call for redemption, exercise of the repurchase right set forth in
Article XIV or otherwise.


                                       -5-


<PAGE>


         ["Non-electing Share" has the meaning specified in Section 12.11.](10)

         "Notice Date" has the meaning specified in Section 2.2.

         "Notice of Default" has the meaning specified in Section 5.1.

         "Officers' Certificate" means a certificate signed by (i) the Chairman
of the Board, a Vice Chairman of the Board, the Chief Executive Officer, the
President, an Executive Vice President or a Vice President and by (ii) the
principal financial officer, the Treasurer, an Assistant Treasurer, the
Secretary, or an Assistant Secretary of the Company, and delivered to the
Trustee. One of the officers signing an Officers' Certificate given pursuant to
Section 10.8 shall be the principal executive, financial or accounting officer
of the Company.

         "Opinion of Counsel" means a written opinion of counsel, who may be
counsel for the Company (including internal counsel) and who shall be reasonably
acceptable to the Trustee.

         "Outstanding", when used with respect to Securities, means, as of the
date of determination, all Securities theretofore authenticated and delivered
under this Indenture, except:

                 (i) Securities theretofore canceled by the Trustee or delivered
         to the Trustee for cancellation;

                 (ii) Securities for the payment or redemption of which money in
         the necessary amount has been theretofore deposited with the Trustee or
         any Paying Agent (other than the Company) in trust or set aside and
         segregated in trust by the Company (if the Company shall act as its own
         Paying Agent) for the Holders of such Securities; provided that, if
         such Securities are to be redeemed, notice of such redemption has been
         duly given pursuant to this Indenture or provision therefor
         satisfactory to the Trustee has been made;

                 (iii) Securities which have been paid pursuant to Section 3.6
         or in exchange for or in lieu of which other Securities have been
         authenticated and delivered pursuant to this Indenture, other than any
         such Securities in respect of which there shall have been presented to
         the Trustee proof satisfactory to it that such Securities are held by a
         bona fide purchaser in whose hands such Securities are valid
         obligations of the Company[; and

                 (iv) Securities converted into Common Stock pursuant to
         Article XII](11);

  provided, however, that in determining whether the Holders of the requisite
  principal amount of Outstanding Securities are present at a meeting of Holders
  for quorum purposes or have given, made or taken any request, demand,
  authorization, direction, notice, consent or waiver or other


----------

        (10) INSERT IF SECURITIES ARE CONVERTIBLE

        (11) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -6-


<PAGE>


action hereunder as of any date, Securities owned by the Company or any other
obligor upon the Securities or any Affiliate of the Company or such other
obligor shall be disregarded and deemed not to be Outstanding, except that, in
determining whether the Trustee shall be protected in relying upon any such
determination as to the presence of a quorum or upon any such request, demand,
authorization, direction, notice, consent, waiver or other action, only
Securities which a Responsible Officer of the Trustee has been notified in
writing to be so owned shall be so disregarded. Securities so owned which have
been pledged in good faith may be regarded as Outstanding if the pledgee is not
the Company or any other obligor upon the Securities or any Affiliate of the
Company or such other obligor, and the Trustee shall be protected in relying
upon an Officers' Certificate to such effect.

         "Over-allotment Option" has the meaning specified in Section 3.1.

         "Paying Agent" means any Person authorized by the Company to pay the
principal of or any premium or interest on any Securities on behalf of the
Company and, except as otherwise specifically set forth herein, such term shall
include the Company if it shall act as its own Paying Agent. The Company has
initially appointed the Trustee as its Paying Agent pursuant to Section 10.2
hereof.

         "Payment Blockage Notice" has the meaning specified in Section 13.2.

         "Person" means any individual, corporation, limited liability company,
partnership, joint venture, trust, estate, unincorporated organization or
government or any agency or political subdivision thereof.

         ["Place of Conversion" has the meaning specified in Section 3.1.](12)

         "Place of Payment" has the meaning specified in Section 3.1.

         "Predecessor Security" of any particular Security means every previous
Security evidencing all or a portion of the same debt as that evidenced by such
particular Security; and, for the purposes of this definition, any Security
authenticated and delivered under Section 3.6 in exchange for or in lieu of a
mutilated, destroyed, lost or stolen Security shall be deemed to evidence the
same debt as the mutilated, destroyed, lost or stolen Security.

         "Privately Placed Note" means that certain 4.75% Convertible 
Subordinated Note Due 2006, No. R-1 issued by the Company to the holder 
thereof on May 1, 2001, in the aggregate principal amount of $10,000,000.

         "Record Date" means any Regular Record Date or Special Record Date.

         "Record Date Period" means the period from the close of business of any
Regular Record Date next preceding any Interest Payment Date to the opening of
business on such Interest Payment Date.


----------

        (12) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -7-


<PAGE>


         "Redemption Date", when used with respect to any Security to be
redeemed, means the date fixed for such redemption by or pursuant to this
Indenture.

         "Redemption Price", when used with respect to any Security to be
redeemed, means the price at which it is to be redeemed pursuant to this
Indenture.

         "Regular Record Date" for interest payable in respect of any Security
on any Interest Payment Date means the ___________ or __________ (whether or not
a Business Day), as the case may be, next preceding such Interest Payment Date.

         "Representative" means the (a) indenture trustee or other trustee,
agent or representative for any Senior Debt or (b) with respect to any Senior
Debt that does not have any such trustee, agent or other representative, (i) in
the case of such Senior Debt issued pursuant to an agreement providing for
voting arrangements as among the holders or owners of such Senior Debt, any
holder or owner of such Senior Debt acting with the consent of the required
persons necessary to bind such holders or owners of such Senior Debt and (ii) in
the case of all other such Senior Debt, the holder or owner of such Senior Debt.

         "Repurchase Date" has the meaning specified in Section 14.1.

         "Repurchase Price" has the meaning specified in Section 14.1.

         "Responsible Officer", when used with respect to the Trustee, means any
officer within the Corporate Trust Office of the Trustee, including without
limitation, any vice president, assistant vice president, assistant treasurer,
corporate trust officer or other employee of the Trustee customarily performing
functions similar to those performed by any of the above designated officers,
and also means, with respect to a particular corporate trust matter, any other
officer to whom such matter is referred because of his knowledge and familiarity
with the particular subject.

         "Securities" has the meaning ascribed to it in the first paragraph
under the caption "Recitals of the Company" and more particularly means any
Securities authenticated and delivered under this Indenture.

         "Securities Act" means the United States Securities Act of 1933 (or any
successor statute), as amended from time to time.

         "Security Register" and "Security Registrar" have the respective
meanings specified in Section 3.5.

         "Senior Debt" means the principal of (and premium, if any) and interest
(including all interest accruing subsequent to the commencement of any
bankruptcy or similar proceeding, whether or not a claim for post-petition
interest is allowable as a claim in any such proceeding) on, and all fees,
expenses and other amounts payable in connection with, the following, whether

                                      -8-


<PAGE>


absolute or contingent, secured or unsecured, due or to become due, 
outstanding on the date of this Indenture or thereafter created, incurred or 
assumed: (a) indebtedness of the Company evidenced by a credit or loan 
agreement, note, bond, debenture or other written obligation (including 
without limitation indebtedness that is convertible or exchangeable for 
securities of the Company), (b) all obligations of the Company for money 
borrowed, (c) all obligations of the Company evidenced by a note or similar 
instrument given in connection with the acquisition of any businesses, 
properties or assets of any kind, (d) obligations of the Company (i) as 
lessee under leases required or permitted to be capitalized on the balance 
sheet of the lessee under generally accepted accounting principles and (ii) 
as lessee under other leases for facilities, equipment or other assets, 
whether or not capitalized, entered into or leased for financing purposes 
(including so-called "synthetic leases"), as determined in good faith by the 
Company, (e) all obligations of the Company under interest rate and currency 
swaps, caps, floors, collars, hedge agreements, currency spot and forward 
contracts or similar agreements or arrangements including, without 
limitation, agreements and arrangements intended to protect the Company from 
fluctuations in interest or currency exchange rates or commodity prices, (f) 
all obligations of the Company with respect to letters of credit, bankers' 
guarantees or bankers' acceptances and similar facilities (including 
reimbursement obligations with respect to the foregoing), (g) all standby 
fees due and payable to lending institutions with respect to credit 
facilities or letters of credit, (h) all obligations of the Company issued or 
assumed as the deferred purchase price of any business, property, assets 
(including intangibles) or services (but excluding trade accounts payable and 
accrued liabilities that constitute liabilities arising in the ordinary 
course of business as determined in good faith by the Company), (i) all 
obligations of the type referred to in clauses (a) through (h) above of 
another Person and all dividends of another Person, the payment of which, in 
either case, the Company has assumed or guaranteed, or for which the Company 
is responsible or liable, directly or indirectly, jointly or severally, as 
obligor, guarantor or otherwise, or which is secured by a lien on the 
property of the Company, and (j) renewals, extensions, deferrals, 
modifications, amendments, replacements, restatements and refundings of, or 
any indebtedness or obligation issued in exchange for, any such indebtedness 
or obligation described in clauses (a) through (i) of this paragraph; 
provided, however, that Senior Debt shall not include the Securities, the 
Privately Placed Note, or any such indebtedness or obligation if the terms of 
such indebtedness or obligation (or the terms of the instrument under which, 
or pursuant to which it is issued) expressly provide that such indebtedness 
or obligation is not superior in right of payment to the Securities.

         "Significant Subsidiary" means, with respect to any Person, a
Subsidiary of such Person that would constitute a "significant subsidiary" as
such term is defined under Rule 1-02 of Regulation S-X under the Securities Act
and the Exchange Act.

         "Special Record Date" for the payment of any Defaulted Interest means a
date fixed by the Company pursuant to Section 3.7.

         "Stated Maturity", when used with respect to any Security or any
installment of interest thereon, means the date specified in such Security as
the fixed date on which the principal of such Security or such installment of
interest is due and payable.

                                      -9-


<PAGE>


         "Subsidiary" means a corporation more than 50% of the outstanding
voting stock of which is owned, directly or indirectly, by the Company or by one
or more other Subsidiaries, or by the Company and one or more other
Subsidiaries. For the purposes of this definition, "voting stock" means stock or
other similar interests in the corporation which ordinarily has or have voting
power for the election of directors, or persons performing similar functions,
whether at all times or only so long as no senior class of stock or other
interests has or have such voting power by reason of any contingency.

         "Successor Security" of any particular Security means every Security
issued after, and evidencing all or a portion of the same debt as that evidenced
by, such particular Security; and, for the purposes of this definition, any
Security authenticated and delivered under Section 3.6 in exchange for or in
lieu of a mutilated, destroyed, lost or stolen Security shall be deemed to
evidence the same debt as the mutilated, destroyed, lost or stolen Security.

         "Trading Day" means (i) if the Common Stock is quoted on the Nasdaq
National Market or any other system of automated dissemination of quotations of
securities prices, days on which trades may be effected through such system,
(ii) if the Common Stock is listed or admitted for trading on any national or
regional securities exchange, days on which such national or regional securities
exchange is open for business, or (iii) if the Common Stock is not listed on a
national or regional securities exchange or quoted on the Nasdaq National Market
or any other system of automated dissemination of quotation of securities
prices, days on which the Common Stock is traded regular way in the over-the-
counter market and for which a closing bid and a closing asked price for the
Common Stock are available.

         "Trust Indenture Act" means the Trust Indenture Act of 1939, and the
rules and regulations thereunder, as in force at the date as of which this
instrument was executed; provided, however, that in the event the Trust
Indenture Act of 1939 is amended after such date, "Trust Indenture Act" means,
to the extent required by any such amendment, the Trust Indenture Act of 1939,
and the rules and regulations thereunder, as so amended.

         "Trustee" means the Person named as the "Trustee" in the first
paragraph of this instrument until a successor Trustee shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Trustee" shall mean such successor Trustee.

         "Underwriting Agreement" means the Underwriting Agreement, dated as of
____________________, ______, among the Company and
_____________________________, as underwriters relating to the offering and sale
of the Securities.

         "United States" means the United States of America (including the
States and the District of Columbia), its territories, its possessions and other
areas subject to its jurisdiction (its "possessions" including Puerto Rico, the
U.S. Virgin Islands, Guam, American Samoa, Wake Island and the Northern Mariana
Islands).

                                      -10-


<PAGE>

         SECTION 1.2 COMPLIANCE CERTIFICATES AND OPINIONS.

         Upon any application or request by the Company to the Trustee to take
any action under any provision of this Indenture, the Company shall furnish to
the Trustee an Officers' Certificate stating that all conditions precedent, if
any, provided for in this Indenture relating to the proposed action have been
complied with and, if required by the Trust Indenture Act, an Opinion of Counsel
stating that in the opinion of such counsel all such conditions precedent, if
any, have been complied with, except that in the case of any such application or
request as to which the furnishing of such documents is specifically required by
any provision of this Indenture relating to such particular application or
request, no additional certificate or opinion need be furnished.

         Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this Indenture (including certificates
provided for in Section 10.7) shall include:

                 (1) a statement that each individual signing such certificate
         or opinion has read such covenant or condition and the definitions
         herein relating thereto;

                 (2) a brief statement as to the nature and scope of the
         examination or investigation upon which the statements or opinions
         contained in such certificate or opinion are based;

                 (3) a statement that, in the opinion of each such individual,
         he has made such examination or investigation as is necessary to enable
         him to express an informed opinion as to whether or not such covenant
         or condition has been complied with; and

                 (4) a statement as to whether, in the opinion of each such
         individual, such condition or covenant has been complied with.

         SECTION 1.3 FORM OF DOCUMENTS DELIVERED TO THE TRUSTEE.

         In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to such matters in one or several documents.

         Any certificate or opinion of an officer of the Company may be based,
insofar as it relates to legal matters, upon a certificate or opinion of, or
representations by, counsel, unless such officer knows, or in the exercise of
reasonable care should know, that the certificate or opinion or representations
with respect to the matters upon which such certificate or opinion is based are
erroneous. Any such certificate or opinion of counsel may be based, insofar as
it relates to factual matters, upon a certificate or opinion of, or
representations by, an officer or officers of the 

                                      -11-


<PAGE>


Company or any other Person stating that the information with respect to such
factual matters is in the possession of the Company or such other Person, unless
such counsel knows that the certificate or opinion or representations with
respect to such matters are erroneous.

         Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Indenture, they may, but need not, be consolidated and
form one instrument.

         SECTION 1.4  ACTS OF HOLDERS.

         (1) Any request, demand, authorization, direction, notice, consent,
waiver or other action provided or permitted by this Indenture to be given, made
or taken by Holders may be embodied in and evidenced by (A) one or more
instruments of substantially similar tenor signed by such Holders in person or
by an agent or proxy duly appointed in writing by such Holders or (B) the record
of Holders voting in favor thereof, either in person or by proxies duly
appointed in writing, at any meeting of Holders duly called and held in
accordance with the provisions of Article IX. Such action shall become effective
when such instrument or instruments or record is delivered to the Trustee and,
where it is hereby expressly required, to the Company. The Trustee shall
promptly deliver to the Company copies of all such instruments and records
delivered to the Trustee. Such instrument or instruments and records (and the
action embodied therein and evidenced thereby) are herein sometimes referred to
as the "Act" of the Holders signing such instrument or instruments and so voting
at such meeting. Proof of execution of any such instrument or of a writing
appointing any such agent or proxy, or of the holding by any Person of a
Security, shall be sufficient for any purpose of this Indenture and (subject to
Section 6.1) conclusive in favor of the Trustee and the Company if made in the
manner provided in this Section. The record of any meeting of Holders shall be
proved in the manner provided in Section 9.6.

         (2) The fact and date of the execution by any Person of any such
instrument or writing may be proved by the affidavit of a witness of such
execution or by a certificate of a notary public or other officer authorized by
law to take acknowledgments of deeds, certifying that the individual signing
such instrument or writing acknowledged to him the execution thereof. Where such
execution is by a signer acting in a capacity other than his individual
capacity, such certificate or affidavit shall also constitute sufficient proof
of his authority.

         (3) The principal amount and serial number of any Security held by any
Person, and the date of his holding the same, shall be proved by the Security
Register.

         (4) The fact and date of execution of any such instrument or writing
and the authority of the Person executing the same may also be proved in any
other manner which the Trustee deems sufficient; and the Trustee may in any
instance require further proof with respect to any of the matters referred to in
this Section 1.4.

                                      -12-


<PAGE>


         (5) The Company may set any day as the record date for the purpose of
determining the Holders entitled to give or take any request, demand,
authorization, direction, notice, consent, waiver or other action, or to vote on
any action, authorized or permitted by this Indenture to be given or taken by
Holders. Promptly and in any case not later than ten days after setting a record
date, the Company shall notify the Trustee and the Holders of such record date.
If not set by the Company prior to the first solicitation of a Holder made by
any Person in respect of any such action, or, in the case of any such vote,
prior to such vote, the record date for any such action or vote shall be the
30th day (or, if later, the date of the most recent list of Holders required to
be provided pursuant to Section 15.1) prior to such first solicitation or vote,
as the case may be. With regard to any record date, the Holders on such date (or
their duly appointed agents or proxies), and only such Persons, shall be
entitled to give or take, or vote on, the relevant action, whether or not such
Holders remain Holders after such record date. Notwithstanding the foregoing,
the Company shall not set a record date for, and the provisions of this
paragraph shall not apply with respect to, any notice, declaration or direction
referred to in the next paragraph.

         Upon receipt by the Trustee from any Holder of (i) any notice of
default or breach referred to in Section 5.1(4) or 5.1(5), if such default or
breach has occurred and is continuing and the Trustee shall not have given such
a notice to the Company, (ii) any declaration of acceleration referred to in
Section 5.2, if an Event of Default has occurred and is continuing and the
Trustee shall not have given such a declaration to the Company, or (iii) any
direction referred to in Section 5.12, if the Trustee shall not have taken the
action specified in such direction, then, with respect to clauses (ii) and
(iii), a record date shall automatically and without any action by the Company
or the Trustee be set for determining the Holders entitled to join in such
declaration or direction, which record date shall be the close of business on
the tenth day (or, if such day is not a Business Day, the first Business Day
thereafter) following the day on which the Trustee receives such declaration or
direction, and, with respect to clause (i), the Trustee may set any day as a
record date for the purpose of determining the Holders entitled to join in such
notice of default. Promptly after such receipt by the Trustee of any such
declaration or direction referred to in clause (ii) or (iii), and promptly after
setting any record date with respect to clause (i), and as soon as practicable
thereafter, the Trustee shall notify the Company and the Holders of any such
record date so fixed. The Holders on such record date (or their duly appointed
agents or proxies), and only such Persons, shall be entitled to join in such
notice, declaration or direction, whether or not such Holders remain Holders
after such record date; provided that, unless such notice, declaration or
direction shall have become effective by virtue of Holders of the requisite
principal amount of Securities on such record date (or their duly appointed
agents or proxies) having joined therein on or prior to the 90th day after such
record date, such notice, declaration or direction shall automatically and
without any action by any Person be canceled and of no further effect. Nothing
in this paragraph shall be construed to prevent a Holder (or a duly appointed
agent or proxy thereof) from giving, before or after the expiration of such
90-day period, a notice, declaration or direction contrary to or different from,
or, after the expiration of such period, identical to, the notice, declaration
or direction to which such record date relates, in which event a new record date
in respect thereof shall be set pursuant to this paragraph. In addition, nothing
in this paragraph shall be construed to render ineffective any notice,
declaration or direction of the type referred to in this paragraph given at any
time to the Trustee and the 

                                      -13-


<PAGE>


Company by Holders (or their duly appointed agents or proxies) of the requisite
principal amount of Securities on the date such notice, declaration or direction
is so given.

         (6) Except as provided in Sections 5.12 and 5.13, any request, demand,
authorization, direction, notice, consent, election, waiver or other Act of the
Holder of any Security shall bind every future Holder of the same Security and
the Holder of every Security issued upon the registration of transfer thereof or
in exchange therefor or in lieu thereof in respect of anything done, omitted or
suffered to be done by the Trustee or the Company in reliance thereon, whether
or not notation of such action is made upon such Security.

         (7) The provisions of this Section 1.4 are subject to the provisions of
Section 9.5.

         SECTION 1.5 NOTICES, ETC. TO THE TRUSTEE AND THE COMPANY.

         Any request, demand, authorization, direction, notice, consent,
election, waiver or other Act of Holders or other document provided or permitted
by this Indenture to be made upon, given or furnished to, or filed with,

         (1) the Trustee by any Holder or by the Company shall be sufficient for
every purpose hereunder if made, given, furnished or filed in writing to or with
a Responsible Officer of the Trustee and received at its Corporate Trust Office,
Attention: ___________________ .

         (2) the Company by the Trustee or by any Holder shall be sufficient for
every purpose hereunder (unless otherwise herein expressly provided) if in
writing, mailed, first-class postage prepaid, or telecopied and confirmed by
mail, first-class postage prepaid, or delivered by hand or overnight courier,
addressed to the Company at 5 Carlisle Road, Westford, Massachusetts 01886,
Attention: Chief Financial Officer, or at any other address previously furnished
in writing to the Trustee by the Company.

         SECTION 1.6  NOTICE TO HOLDERS; WAIVER.

         Except as otherwise expressly provided herein, where this Indenture
provides for notice to Holders of any event, such notice shall be sufficiently
given to Holders if in writing and mailed, first-class postage prepaid or
delivered by an overnight delivery service, to each Holder affected by such
event, at the address of such Holder as it appears in the Security Register, not
earlier than the earliest date and not later than the latest date prescribed for
the giving of such notice.

         Neither the failure to mail such notice, nor any defect in any notice
so mailed, to any particular Holder shall affect the sufficiency of such notice
with respect to other Holders. In case by reason of the suspension of regular
mail service or by reason of any other cause it shall be impracticable to give
such notice by mail, then such notification to Holders as shall be made in 

                                      -14-


<PAGE>


such manner with the approval of the Trustee, which approval shall not be
unreasonably withheld or delayed, shall constitute a sufficient notification to
such Holders for every purpose hereunder.

         Such notice shall be deemed to have been given when such notice is
received.

         Where this Indenture provides for notice in any manner, such notice may
be waived in writing by the Person entitled to receive such notice, either
before or after the event, and such waiver shall be the equivalent of such
notice. Waivers of notice by Holders shall be filed with the Trustee, but such
filing shall not be a condition precedent to the validity of any action taken in
reliance upon such waiver.

         SECTION 1.7 EFFECT OF HEADINGS AND TABLE OF CONTENTS.

         The Article and Section headings herein and the Table of Contents are
for convenience only and shall not affect the construction hereof.

         SECTION 1.8 SUCCESSORS AND ASSIGNS.

         All covenants and agreements in this Indenture by the Company shall
bind its successors and assigns, whether so expressed or not.

         SECTION 1.9 SEPARABILITY CLAUSE.

         In case any provision in this Indenture or the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

         SECTION 1.10 BENEFITS OF INDENTURE.

         Except as provided in the next sentence, nothing in this Indenture or
in the Securities, express or implied, shall give to any Person, other than the
parties hereto and their successors and assigns hereunder and the Holders, any
benefit or legal or equitable right, remedy or claim under this Indenture. The
provisions of Article XIII are intended to be for the benefit of, and shall be
enforceable directly by, the holders of Senior Debt.

         SECTION 1.11 GOVERNING LAW.

         THIS INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, THE UNITED STATES OF AMERICA,
WITHOUT REGARD TO THE CONFLICTS OF LAWS PRINCIPLES THEREOF.

                                      -15-


<PAGE>


         SECTION 1.12 LEGAL HOLIDAYS.

         In any case where any Interest Payment Date, Redemption Date,
Repurchase Date or Stated Maturity of any Security [or the last day on which a
Holder has a right to convert his Security(13)] shall not be a Business Day at a
Place of Payment [or Place of Conversion, as the case may be](14), then
(notwithstanding any other provision of this Indenture or of the Securities)
payment of principal of, premium, if any, or interest on, or the payment of the
Redemption Price or Repurchase Price (whether the same is payable in cash or in
shares of Common Stock) with respect to[, or delivery for conversion of,](15)
such Security need not be made at such Place of Payment [or Place of Conversion,
as the case may be,](16) on or by such day, but may be made on or by the next
succeeding Business Day at such Place of Payment [or Place of Conversion, as the
case may be,](17) with the same force and effect as if made on the Interest
Payment Date, Redemption Date or Repurchase Date, or at the Stated Maturity [or
by such last day for conversion](18); provided, however, that in the case that
payment is made on such succeeding Business Day, no interest shall accrue on the
amount so payable for the period from and after such Interest Payment Date,
Redemption Date, Repurchase Date, Stated Maturity [or last day for
conversion](19), as the case may be.

         SECTION 1.13 CONFLICT WITH TRUST INDENTURE ACT.

         If any provision hereof limits, qualifies or conflicts with a provision
of the Trust Indenture Act that is required under the Trust Indenture Act to be
a part of and govern this Indenture, the latter provision shall control. If any
provision of this Indenture modifies or excludes any provision of the Trust
Indenture Act that may be so modified or excluded, the latter provision shall be
deemed to apply to this Indenture as so modified or to be excluded, as the case
may be. Until such time as this Indenture shall be qualified under the Trust
Indenture Act, this Indenture, the Company and the Trustee shall be deemed for
all purposes hereof to be subject to and governed by the Trust Indenture Act to
the same extent as would be the case if this Indenture were so qualified on the
date hereof.

----------

        (13) INSERT IF SECURITIES ARE CONVERTIBLE

        (14) INSERT IF SECURITIES ARE CONVERTIBLE

        (15) INSERT IF SECURITIES ARE CONVERTIBLE

        (16) INSERT IF SECURITIES ARE CONVERTIBLE

        (17) INSERT IF SECURITIES ARE CONVERTIBLE

        (18) INSERT IF SECURITIES ARE CONVERTIBLE

        (19) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -16-


<PAGE>


                                   ARTICLE II

                                 SECURITY FORMS

         SECTION 2.1 FORM GENERALLY.

         The Securities shall be in substantially the form set forth in this
Article, with such appropriate insertions, omissions, substitutions and other
variations as are required or permitted by this Indenture, and may have such
letters, numbers or other marks of identification and such legends or
endorsements placed thereon as may be required to comply with the rules of any
securities exchange, the Internal Revenue Code of 1986, as amended, and
regulations thereunder (the "Code"), or as may, consistent herewith, be
determined by the officers executing such Securities, as evidenced by their
execution thereof. All Securities shall be issued in registered form, as opposed
to bearer form.

         The Trustee's certificates of authentication shall be in substantially
the form set forth in Section 2.3.

         [Conversion notices shall be in substantially the form set forth in
Section 2.4.](20)

         Repurchase notices shall be substantially in the form set forth in
Section 2.2.

         The Securities shall be printed, lithographed, typewritten or engraved
or produced by any combination of these methods or may be produced in any other
manner permitted by the rules of any automated quotation system or securities
exchange (including on steel engraved borders if so required by any securities
exchange upon which the Securities may be listed) on which the Securities may be
quoted or listed, as the case may be or, if the Securities are not listed on a
securities exchange or automated quotation system, in any other manner approved
by the Company, all as determined by the officers executing such Securities, as
evidenced by their execution thereof.

         Upon their original issuance, Securities shall be issued in the form of
one or more Global Securities without interest coupons and shall be registered
in the name of DTC, as Depositary, or its nominee and deposited with the
Trustee, as custodian for DTC, for credit by DTC to the respective accounts of
beneficial owners of the Securities represented thereby (or such other accounts
as they may direct).

         SECTION 2.2 FORM OF SECURITY.

[FORM OF FACE]

         [THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY:


----------

        (20) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -17-


<PAGE>


         THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF THE DEPOSITARY OR A
NOMINEE OF THE DEPOSITARY, WHICH MAY BE TREATED BY THE COMPANY, THE TRUSTEE AND
ANY AGENT THEREOF AS OWNER AND HOLDER OF THIS SECURITY FOR ALL PURPOSES.

         THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY
FOR WHICH THE DEPOSITORY TRUST COMPANY IS TO BE THE DEPOSITARY:

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE 
OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE 
ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND 
ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH 
OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY 
PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN 
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF 
FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE 
REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

         UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN
DEFINITIVE REGISTERED FORM IN THE LIMITED CIRCUMSTANCES REFERRED TO IN THE
INDENTURE, THIS GLOBAL SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE
DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO
THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY
SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR
DEPOSITARY.]

                              SONUS NETWORKS, INC.

______% [CONVERTIBLE](21) SUBORDINATED NOTE DUE _________________, ____

No.____  $ __________________


CUSIP NO. ___________

         SONUS NETWORKS, INC., a corporation duly organized and existing under
the laws of the State of Delaware (herein called the "Company", which term
includes any successor Person

----------

        (21) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -18-


<PAGE>


under the Indenture referred to on the reverse hereof), for value received, 
hereby promises to pay to _________________, or registered assigns, the 
principal sum of ________ United States Dollars (U.S.$______ ) (which 
principal amount may from time to time be increased or decreased to such 
other principal amounts (which, taken together with the principal amounts of 
all other Outstanding Securities, shall not exceed $___________ (or 
$___________ if the Over-allotment Option is exercised in full)) by 
adjustments made on the records of the Trustee hereinafter referred to in 
accordance with the Indenture) on __________________, ______ and to pay 
interest thereon, from _________, _____, or from the most recent Interest 
Payment Date (as defined below) to which interest has been paid or duly 
provided for, semi-annually in arrears on __________________ and 
__________________ in each year (each, an "Interest Payment Date"), 
commencing _______, _____, at the rate of _____% per annum, until the 
principal hereof is due, and at the rate of _____% per annum on any overdue 
principal and premium, if any, and, to the extent permitted by law, on any 
overdue interest. The interest so payable, and punctually paid or duly 
provided for, on any Interest Payment Date will, as provided in the 
Indenture, be paid to the Person in whose name this Security (or one or more 
Predecessor Securities) is registered at the close of business on the Regular 
Record Date for such interest, which shall be the _________ or _________ 
(whether or not a Business Day), as the case may be, next preceding such 
Interest Payment Date. Except as otherwise provided in the Indenture, any 
such interest not so punctually paid or duly provided for will forthwith 
cease to be payable to the Holder on such Regular Record Date and may either 
be paid to the Person in whose name this Security (or one or more Predecessor 
Securities) is registered at the close of business on a Special Record Date 
for the payment of such Defaulted Interest to be fixed by the Company, notice 
whereof shall be given to Holders not less than 10 days prior to such Special 
Record Date, or be paid at any time in any other lawful manner not 
inconsistent with the requirements of any automated quotation system or 
securities exchange on which the Securities may be quoted or listed, and upon 
such notice as may be required by such exchange, all as more fully provided 
in the Indenture. Payments of principal shall be made upon the surrender of 
this Security at the option of the Holder at the Corporate Trust Office of 
the Trustee, or at such other office or agency of the Company as may be 
designated by it for such purpose in the Borough of Manhattan, The City of 
New York, in such lawful monies of the United States of America as at the 
time of payment shall be legal tender for the payment of public and private 
debts, or at such other offices or agencies as the Company may designate, by 
United States Dollar check drawn on, or wire transfer to, a United States 
Dollar account (such a wire transfer to be made only to a Holder of an 
aggregate principal amount of Securities in excess of U.S. $2,000,000 and 
only if such Holder shall have furnished wire instructions in writing to the 
Trustee no later than 15 days prior to the relevant payment date) maintained 
by the payee with a bank in the Borough of Manhattan, The City of New York. 
Payment of interest on this Security may be made by United States Dollar 
check mailed to the address of the Person entitled thereto as such address 
shall appear in the Security Register, or, upon written application by the 
Holder to the Security Registrar setting forth wire instructions not later 
than the relevant Record Date, by wire transfer to a United States Dollar 
account (such a wire transfer to be made only to a Holder of an aggregate 
principal amount of Securities in excess of U.S. $2,000,000 and only if such 
Holder shall have furnished wire instructions in writing to the Trustee no 
later than 15 days prior to the relevant payment date) maintained by the 
payee with a bank in the Borough of Manhattan, The

                                      -19-


<PAGE>


City of New York. Except as specifically provided herein and in the Indenture,
the Company shall not be required to make any payment with respect to any tax,
assessment or other governmental charge imposed by any government or any
political subdivision or taxing authority thereof or therein.

         Interest on the Securities shall be computed on the basis of a 
360-day year of twelve 30-day months.

         Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

         Unless the certificate of authentication hereon has been executed by
the Trustee referred to on the reverse hereof or an Authenticating Agent by the
manual signature of one of their respective authorized signatories, this
Security shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

         IN WITNESS WHEREOF, the Company has caused this Security to be duly
executed.


                                       SONUS NETWORKS, INC.

                                       By:
                                          _____________________________________
                                       Name:
                                       Title:

Attest:

By:
   ________________________________
Name:
Title:

TRUSTEE'S CERTIFICATE OF AUTHENTICATION

This is one of the Securities referred to in the within-mentioned Indenture.

     Dated:______________________________
     as Trustee

     By:
        ________________________________
        Authorized Signatory


                                [FORM OF REVERSE]

                                      -20-


<PAGE>


This Security is one of a duly authorized issue of securities of the Company
designated as its "_____% [Convertible](22) Subordinated Notes due
__________________" (herein called the "Securities"), limited in aggregate
principal amount to U.S. $___________ (or $___________ if the Over-allotment
Option is exercised in full), issued and to be issued under an Indenture, dated
as of _______________, _____ (herein called the "Indenture"), between the
Company and _________________, as Trustee (herein called the "Trustee", which
term includes any successor trustee under the Indenture), and to which Indenture
and all indentures supplemental thereto reference is hereby made for a statement
of the respective rights, limitations of rights, duties and immunities
thereunder of the Company, the Trustee, the holders of Senior Debt and the
Holders of the Securities and of the terms upon which the Securities are, and
are to be, authenticated and delivered. As provided in the Indenture and subject
to certain limitations therein set forth, Securities are exchangeable for a like
aggregate principal amount of Securities of any authorized denominations as
requested by the Holder surrendering the same upon surrender of the Security or
Securities to be exchanged, at the Corporate Trust Office of the Trustee. The
Trustee upon such surrender by the Holder will issue the new Securities in the
requested denominations. No sinking fund is provided for the Securities. The
Securities are subject to redemption by the Company, in whole or in part, at any
time prior to __________________, ________, upon notice as set forth in Section
11.5 of the Indenture, at a redemption price equal to the principal amount of
the Securities to be redeemed plus accrued and unpaid interest, if any, to the
Redemption Date if the Closing Price of the Common Stock shall have
________________ for at least 20 Trading Days in any 30-Trading Day period
ending on the Trading Day prior to the date of mailing of the notice of
redemption pursuant to Section 11.5 of the Indenture (the "Notice Date"). Upon
any such redemption, the Company shall make an additional payment (the
"Make-Whole Payment") with respect to the Securities called for redemption to
holders on the Notice Date in an amount equal to $_______ per U.S. $1,000
Security, less the amount of any interest actually paid on such Security prior
to the Notice Date. The Company shall make the Make-Whole Payment on all
Securities called for redemption[,including any Securities converted into Common
Stock pursuant to the terms of the Indenture after the Notice Date and prior to
the Redemption Date.](23) The Company may make the Make-Whole Payment, at its
option, in cash, in shares of Common Stock or through a combination of cash and
shares of Common Stock. For purposes of this paragraph, the fair market value of
shares of Common Stock shall be determined by the Company and shall be equal to
___% of the average of the Closing Price Per Share for the five consecutive
Trading Days immediately preceding the Redemption Date.

         The Securities are also subject to redemption at the option of the
Company at any time on or after __________________,___ in whole or in part, upon
not less than 30 nor more than 60 days notice to the Holders prior to the
Redemption Date at the Redemption Prices (expressed as percentages of the
principal amount) set forth below.


----------

        (22) INSERT IF SECURITIES ARE CONVERTIBLE

        (23) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -21-


<PAGE>


         The following table sets forth the Redemption Prices (expressed as
percentages of the principal amount) if such Security is redeemed during the
12-month period beginning on __________ of the following years:


<TABLE>
<CAPTION>
YEAR                             REDEMPTION PRICE
<S>                              <C>
</TABLE>


and thereafter at a Redemption Price equal to _____% of the principal amount,
together, in each case, with accrued interest to the Redemption Date; provided,
however, that interest installments on Securities whose Stated Maturity is on or
prior to such Redemption Date will be payable to the Holders of such Securities,
or one or more Predecessor Securities, of record at the close of business on the
relevant Record Dates referred to on the face hereof, all as provided in the
Indenture.

         In the event of a redemption of the Securities, the Company will not be
required (a) to register the transfer or exchange of Securities for a period of
15 days immediately preceding the date notice is given identifying the serial
numbers of the Securities called for such redemption or (b) to register the
transfer or exchange of any Security, or portion thereof, called for redemption.
In any case where the due date for the payment of the principal of, premium, if
any, or interest on any Security [or the last day on which a Holder has a right
to convert his Security](24) shall be, at any Place of Payment [or Place of
Conversion, as the case may be,](25) a day on which banking institutions at such
Place of Payment [or Place of Conversion](26) are authorized or obligated by law
or executive order to close, then payment of principal, premium, if any, or
interest, [or delivery for conversion of such Security](27) need not be made on
or by such date at such place but may be made on or by the next succeeding day
at such place which is not a day on which banking institutions are authorized or
obligated by law or executive order to close, with the same force and effect as
if made on the date for such payment or the date fixed for redemption or
repurchase[, or by such last day for conversion,](28) and no interest shall
accrue on the amount so payable for the period from and after such due date.

         [Subject to and upon compliance with the provisions of the Indenture,
the Holder of this Security is entitled, at his option, at any time on or before
the close of business on the date of 

----------

        (24) INSERT IF SECURITIES ARE CONVERTIBLE

        (25) INSERT IF SECURITIES ARE CONVERTIBLE

        (26) INSERT IF SECURITIES ARE CONVERTIBLE

        (27) INSERT IF SECURITIES ARE CONVERTIBLE

        (28) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -22-


<PAGE>


Maturity, or in case this Security or a portion hereof is called for redemption
or the Holder hereof has exercised his right to require the Company to
repurchase this Security or such portion hereof, then in respect of this
Security until and including, but (unless the Company defaults in making the
payment due upon redemption or repurchase, as the case may be) not after, the
close of business on the Business Day immediately preceding the Redemption Date
or the Repurchase Date, as the case may be, to convert this Security (or any
portion of the principal amount hereof that is an integral multiple of
U.S.$1,000, provided that the unconverted portion of such principal amount is an
integral multiple of U.S.$1,000) into fully paid and nonassessable shares of
Common Stock of the Company at an initial Conversion Rate of ______ shares of
Common Stock for each U.S.$1,000 principal amount of Securities (or at the
current adjusted Conversion Rate if an adjustment has been made as provided in
the Indenture) by surrender of this Security, duly endorsed or assigned to the
Company or in blank and, in case such surrender shall be made during the period
from the close of business on any Regular Record Date next preceding any
Interest Payment Date to the opening of business on such Interest Payment Date
(except if this Security or portion thereof has been called for redemption on a
Redemption Date or is repurchasable on a Repurchase Date occurring, in either
case, during such period and, as a result, the right to convert would terminate
in such period), also accompanied by payment in New York Clearing House or other
funds acceptable to the Company of an amount equal to the interest payable on
such Interest Payment Date on the principal amount of this Security then being
converted, and also the conversion notice hereon duly executed, to the Company
at the Corporate Trust Office of the Trustee, or at such other office or agency
of the Company, subject to any laws or regulations applicable thereto and
subject to the right of the Company to terminate the appointment of any
Conversion Agent (as defined below) as may be designated by it for such purpose
in the Borough of Manhattan, The City of New York, or at such other offices or
agencies as the Company may designate in the Borough of Manhattan, The City of
New York (each a "Conversion Agent"), provided, further, that if this Security
or portion hereof has been called for redemption on a Redemption Date or is
repurchasable on a Repurchase Date occurring, in either case, during the period
from the close of business on any Regular Record Date next preceding any
Interest Payment Date to the opening of business on such succeeding Interest
Payment Date, and is surrendered for conversion during such period, then the
Holder of this Security on such Regular Record Date will be entitled to receive
the interest accruing hereon from the Interest Payment Date next preceding the
date of such conversion to such succeeding Interest Payment Date and the Holder
of this Security who converts this Security or a portion hereof during such
period shall not be required to pay such interest upon surrender of this
Security for conversion. Subject to the provisions of the preceding sentence
and, in the case of a conversion after the close of business on the Regular
Record Date next preceding any Interest Payment Date and on or before the close
of business on such Interest Payment Date, to the right of the Holder of this
Security (or any Predecessor Security of record as of such Regular Record Date)
to receive the related installment of interest to the extent and under the
circumstances provided in the Indenture, no cash payment or adjustment is to be
made on conversion for interest accrued hereon from the Interest Payment Date
next preceding the day of conversion, or for dividends on the Common Stock
issued on conversion hereof. The Company shall thereafter deliver to the Holder
the fixed number of shares of Common Stock (together with any cash adjustment,
as provided in the Indenture) into which this Security is convertible and such
delivery will be

                                      -23-


<PAGE>


deemed to satisfy the Company's obligation to pay the principal amount of this
Security. No fractions of shares or scrip representing fractions of shares will
be issued on conversion, but instead of any fractional interest (calculated to
the nearest 1/100th of a share) the Company shall pay a cash adjustment as
provided in the Indenture. The Conversion Rate is subject to adjustment as
provided in the Indenture. In addition, the Indenture provides that in case of
certain consolidations or mergers to which the Company is a party (other than a
consolidation or merger that does not result in any reclassification,
conversion, exchange or cancellation of the Common Stock) or the conveyance,
transfer, sale or lease of all or substantially all of the property and assets
of the Company, the Indenture shall be amended, without the consent of any
Holders, so that this Security, if then Outstanding, will be convertible
thereafter, during the period this Security shall be convertible as specified
above, only into the kind and amount of securities, cash and other property
receivable upon such consolidation, merger, conveyance, transfer, sale or lease
by a holder of the number of shares of Common Stock of the Company into which
this Security could have been converted immediately prior to such consolidation,
merger, conveyance, transfer, sale or lease (assuming such holder of Common
Stock is not a Constituent Person, failed to exercise any rights of election and
received per share the kind and amount received per share by a plurality of
Non-electing Shares). No adjustment in the Conversion Rate will be made until
such adjustment would require an increase or decrease of at least one percent of
such rate, provided that any adjustment that would otherwise be made will be
carried forward and taken into account in the computation of any subsequent
adjustment.](29) If a Change in Control occurs, the Holder of this Security, at
the Holder's option, shall have the right, in accordance with the provisions of
the Indenture, to require the Company to repurchase this Security (or any
portion of the principal amount hereof that is equal to an integral multiple of
$1,000, provided that the portion of the principal amount of this Security to be
Outstanding after such repurchase is an integral multiple of U.S.$1,000) for
cash at a Repurchase Price equal to ____% of the principal amount thereof plus
interest accrued to the Repurchase Date. At the option of the Company as
determined prior to the time of the Change in Control, the Repurchase Price may
be paid in cash or, subject to the conditions provided in the Indenture, by
delivery of shares of Common Stock having a fair market value equal to the
Repurchase Price. For purposes of this paragraph, the fair market value of
shares of Common Stock shall be determined by the Company and shall be equal to
_______% of the average of the Closing Price Per Share for the five consecutive
Trading Days immediately preceding and including the third Trading Day prior to
the Repurchase Date. Whenever in this Security there is a reference, in any
context, to the principal of any Security as of any time, such reference shall
be deemed to include reference to the Repurchase Price payable in respect of
such Security to the extent that such Repurchase Price is, was or would be so
payable at such time, and express mention of the Repurchase Price in any
provision of this Security shall not be construed as excluding the Repurchase
Price so payable in those provisions of this Security when such express mention
is not made; provided, however, that, for the purposes of the second succeeding
paragraph, such reference shall be deemed to include reference to the Repurchase
Price only to the extent the Repurchase Price is payable in cash.

----------

        (29) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -24-


<PAGE>


         The following paragraph shall appear in each Global Security:

         [In the event of a deposit or withdrawal of an interest in this
Security, including an exchange, transfer, redemption, repurchase [or
conversion](30) of this Security in part only, the Trustee, as custodian of the
Depositary, shall make an adjustment on its records to reflect such deposit or
withdrawal in accordance with the Applicable Procedures.]

         [The following paragraph shall appear in each Security that is not a
Global Security:

         In the event of redemption, repurchase [or conversion](31) of this
Security in part only, a new Security or Securities for the unredeemed,
unrepurchased [or unconverted](32) portion hereof will be issued in the name of
the Holder hereof.]

         The indebtedness evidenced by this Security is, to the extent and in
the manner provided in the Indenture, subordinate and subject in right of
payment to the prior payment in full of all Senior Debt of the Company, and this
Security is issued subject to such provisions of the Indenture with respect
thereto. Each Holder of this Security, by accepting the same, (a) agrees to and
shall be bound by such provisions, (b) authorizes and directs the Trustee on his
behalf to take such action as may be necessary or appropriate to effectuate the
subordination so provided and (c) appoints the Trustee his attorney-in-fact for
any and all such purposes.

         If an Event of Default shall occur and be continuing, the principal of
all the Securities, together with accrued interest to the date of declaration,
may be declared due and payable in the manner and with the effect provided in
the Indenture. Upon payment (i) of the amount of principal so declared due and
payable, together with accrued interest to the date of declaration, and (ii) of
interest on any overdue principal and, to the extent permitted by applicable
law, overdue interest, all of the Company's obligations in respect of the
payment of the principal of and interest on the Securities shall terminate.

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities under the Indenture at
any time by the Company and the Trustee with either (a) the written consent of
the Holders of not less than ___________ in principal amount of the Securities
at the time Outstanding, or (b) by the adoption of a resolution, at a meeting of
Holders of the Outstanding Securities at which a quorum is present, by the
Holders of at least _______% in aggregate principal amount of the Outstanding
Securities represented and entitled to vote at such meeting. The Indenture also
contains provisions permitting the Holders of 

----------

        (30) INSERT IF SECURITIES ARE CONVERTIBLE

        (31) INSERT IF SECURITIES ARE CONVERTIBLE

        (32) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -25-


<PAGE>


specified percentages in principal amount of the Securities at the time
Outstanding, on behalf of the Holders of all the Securities, to waive compliance
by the Company with certain provisions of the Indenture and certain past
defaults under the Indenture and their consequences. Any such consent or waiver
by the Holder of this Security shall be conclusive and binding upon such Holder
and upon all future Holders of this Security and of any Security issued in
exchange therefor or in lieu hereof whether or not notation of such consent or
waiver is made upon this Security or such other Security as provided in and
subject to the provisions of the Indenture, the Holder of this Security shall
not have the right to institute any proceeding with respect to the Indenture or
for the appointment of a receiver or trustee or for any other remedy thereunder,
unless such Holder shall have previously given the Trustee written notice of a
continuing Event of Default, the Holders of not less than 25% in principal
amount of the Outstanding Securities shall have made written request to the
Trustee to institute proceedings in respect of such Event of Default as Trustee
and offered the Trustee reasonable indemnity and the Trustee shall not have
received from the Holders of a majority in principal amount of the Securities
Outstanding a direction inconsistent with such request, and shall have failed to
institute any such proceeding, for 60 days after receipt of such notice, request
and offer of indemnity. The foregoing shall not apply to any suit instituted by
the Holder of this Security for the enforcement of any payment of principal
hereof, premium, if any, or interest hereon on or after the respective due dates
expressed herein [or for the enforcement of the right to convert this Security
as provided in the Indenture.](33)

         No reference herein to the Indenture and no provision of this Security
or of the Indenture shall alter or impair the obligation of the Company, which
is absolute and unconditional, to pay the principal of, premium, if any, and
interest on this Security at the times, places and rate, and in the coin or
currency, herein prescribed [or to convert this Security as provided in the
Indenture.](34)

         As provided in the Indenture and subject to certain limitations therein
set forth, the transfer of this Security is registrable in the Security Register
upon surrender of this Security for registration of transfer at the Corporate
Trust Office of the Trustee or at such other office or agency of the Company as
may be designated by it for such purpose in the Borough of Manhattan, The City
of New York (which shall initially be an office or agency of the Trustee), or at
such other offices or agencies as the Company may designate, duly endorsed by,
or accompanied by a written instrument of transfer in form satisfactory to the
Company and the Security Registrar duly executed by, the Holder thereof or his
attorney duly authorized in writing, and thereupon one or more new Securities,
of authorized denominations and for the same aggregate principal amount, will be
issued to the designated transferee or transferees by the Registrar. No service
charge shall be made for any such registration of transfer or exchange, but the
Company may require payment of a sum sufficient to recover any tax or other
governmental charge payable in connection therewith.

----------

        (33) INSERT IF SECURITIES ARE CONVERTIBLE

        (34) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -26-


<PAGE>


         Prior to due presentation of this Security for registration of
transfer, the Company, the Trustee, any Authenticating Agent or any other agent
of the Company or the Trustee may treat the Person in whose name this Security
is registered as the owner hereof for all purposes, whether or not this Security
be overdue, and neither the Company, the Trustee nor any Authenticating Agent or
other agent of the Company or the Trustee shall be affected by notice to the
contrary.

         No recourse for the payment of the principal (and premium, if any or
interest on this Security and no recourse under or upon any obligation, covenant
or agreement of the Company in the Indenture or any indenture supplemental
thereto or in any Security, or because of the creation of any indebtedness
represented thereby, shall be had against any incorporator, stockholder,
employee, agent, officer or director or subsidiary, as such, past, present or
future, of the Company or of any successor corporation, either directly or
through the Company or any successor corporation, whether by virtue of any
constitution, statute or rule of law or by the enforcement of any assessment or
penalty or otherwise, all such liability being, by the acceptance hereof and as
part of consideration for the issue hereof, expressly waived and released.

         THE INDENTURE AND THIS SECURITY SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, UNITED STATES OF AMERICA,
WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF LAWS.

         All terms used in this Security which are defined in the Indenture
shall have the meanings assigned to them in the Indenture.

                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription of the face
of this Security, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM   as tenants in common
TEN ENT   as tenants by the entireties
JT TEN    as joint tenants with right of  survivorship and not as tenants in
          common

UNIF GIFT MIN ACT ____ Custodian ____
                  (Cust)         (Minor)
                  under Uniform Gifts
                  to Minors Act_____

         Additional abbreviations may also be used though not in the above list.

         ELECTION OF HOLDER TO REQUIRE REPURCHASE


                                      -27-


<PAGE>


         (1) Pursuant to Section 14.1 of the Indenture, the undersigned hereby
elects to have this Security repurchased by the Company.

         (2) The undersigned hereby directs the Trustee or the Company to pay it
or ______________ an amount in cash or, at the Company's election, Common Stock
valued as set forth in the Indenture, equal to ______% of the principal amount
to be repurchased (as set forth below), plus interest accrued to the Repurchase
Date, as provided in the Indenture.

Dated:

________________________________

________________________________
Signature(s)

Signature(s) must be guaranteed by an Eligible Guarantor Institution with
membership in an approved signature guarantee program pursuant to Rule 17Ad-15
under the Securities Exchange Act of 1934.


________________________________
Signature Guaranteed


Principal amount to be repurchased (an integral multiple of $1,000):


________________________________


Remaining principal amount, if any, following such repurchase (not less than
U.S. $1,000): ______________

NOTICE: The signature to the foregoing Election must correspond to the Name as
written upon the face of this Security in every particular, without alteration
or any change whatsoever.

SECTION 2.3 FORM OF CERTIFICATE OF AUTHENTICATION.

         The Trustee's certificates of authentication shall be in substantially
the following form:

         This is one of the Securities referred to in the within-mentioned
Indenture.

Dated:[DATE OF AUTHENTICATION]

                                      -28-


<PAGE>


_______________________________________

         ______________________________
         as Trustee

         By:
            __________________________
         Authorized Signatory

         [SECTION 2.4  FORM OF CONVERSION NOTICE.

                                CONVERSION NOTICE

         The undersigned Holder of this Security hereby irrevocably exercises
the option to convert this Security, or any portion of the principal amount
hereof (which is an integral multiple of U.S.$1,000 provided that the
unconverted portion of such principal amount is an integral multiple of
U.S.$1,000) below designated, into shares of Common Stock in accordance with the
terms of the Indenture referred to in this Security, and directs that such
shares, together with a check in payment for any fractional share and any
Securities representing any unconverted principal amount hereof, be delivered to
and be registered in the name of the undersigned unless a different name has
been indicated below. If shares of Common Stock or Securities are to be
registered in the name of a Person other than the undersigned, (a) the
undersigned will pay all transfer taxes payable with respect thereto and (b)
signature(s) must be guaranteed by an Eligible Guarantor Institution with
membership in an approved signature guarantee program pursuant to Rule 17Ad-15
under the Securities Exchange Act of 1934. Any amount required to be paid by the
undersigned on account of interest accompanies this Security.

Dated:
      ________________________________ ________________________________
                    Signature(s)

If shares or Securities are to be registered in the name of a Person other than
the Holder, please print such Person's name and address:


_______________________
(Name)


_______________________

_______________________
(Address)

Social Security or other Identification
Number, if any


                                      -29-


<PAGE>


_______________________
[Signature Guaranteed]

If only a portion of the Securities is to be converted, please indicate:

1.  Principal amount to be converted: U.S. $ ___________

2.  Principal amount and denomination of Securities representing unconverted
    principal amount to be issued:

         Amount: U.S. $___________Denominations: U.S. $____________

(any integral multiple of U.S. $1,000, provided that the unconverted portion of
such principal amount is an integral multiple of U.S. $1,000)](35)

         SECTION 2.5  FORM OF ASSIGNMENT.

         For value received ________________ hereby sell(s), assign(s) and
transfer(s) unto ________________ (Please insert social security or other
identifying number of assignee) the within Security, and hereby irrevocably
constitutes and appoints ____________________as attorney to transfer the said
Security on the books of the Company, with full power of substitution in the
premises.

Dated:
      ________________________________ ________________________________
                    Signature(s)

Signature(s) must be guaranteed by an Eligible Guarantor Institution with
membership in an approved signature guarantee program pursuant to Rule 17Ad-15
under the Securities Exchange Act of 1934.


_______________________
Signature Guaranteed


----------

        (35) INSERT IF SECURITIES ARE CONVERTIBLE



                                      -30-

<PAGE>


                                   ARTICLE III

                                 THE SECURITIES

         SECTION 3.1 TITLE AND TERMS.

         The aggregate principal amount of Securities which may be authenticated
and delivered under this Indenture is limited to U.S. $____________ (or
$_____________ if the Over-allotment Option set forth in the Underwriting
Agreement is exercised in full (the "Over-allotment Option")), except for
Securities authenticated and delivered pursuant to Section 3.4, 3.5, 3.6, 8.5,
11.7[, 12.2](36) or 14.3(5) in exchange for, or in lieu of, other Securities
previously authenticated and delivered under this Indenture.

         The Securities shall be known and designated as the "____%
[Convertible](37) Subordinated Notes due _________, ______" of the Company.
Their Stated Maturity shall be _______________, _____ and they shall bear
interest on their principal amount from ____________, _____, payable
semi-annually in arrears on ________ and ________ in each year, commencing
_________________, ______, at the rate of ____% per annum until the principal
thereof is due and at the rate of ____% per annum on any overdue principal and,
to the extent permitted by law, on any overdue interest; provided, however, that
payments shall only be made on Business Days as provided in Section 1.12.

         The principal of, premium, if any, and interest on the Securities shall
be payable as provided in the form of Securities set forth in Section 2.2, and
the Repurchase Price, whether payable in cash or in shares of Common Stock,
shall be payable at such places as are identified in the Company Notice given
pursuant to Section 14.3 (any city in which any Paying Agent is located being
herein called a "Place of Payment").

         The Securities shall be redeemable at the option of the Company at any
time on or after _________________, ____, in whole or in part, subject to the
conditions and as otherwise provided in Article XI and in the form of Securities
set forth in Section 2.2.

         The Securities are not entitled to the benefit of any sinking fund.

         [The Securities shall be convertible as provided in Article XII (any
city in which any Conversion Agent is located being herein called a "Place of
Conversion").](38)

         The Securities shall be subordinated in right of payment to Senior Debt
of the Company as provided in Article XIII.

         The Securities shall be subject to repurchase by the Company at the
option of the Holders as provided in Article XIV.

----------

        (36) INSERT IF SECURITIES ARE CONVERTIBLE

        (37) INSERT IF SECURITIES ARE CONVERTIBLE

        (38) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -31-


<PAGE>


         SECTION 3.2 DENOMINATIONS.

         The Securities shall be issuable only in registered form, without
coupons, in denominations of U.S. $1,000 and integral multiples thereof.

         SECTION 3.3 EXECUTION, AUTHENTICATION, DELIVERY AND DATING.

         The Securities shall be executed on behalf of the Company by its
Chairman of the Board, its Vice Chairman of the Board, its Chief Executive
Officer, its President, or one of its Vice Presidents, with or without a
corporate seal reproduced thereon, and attested by its Chief Executive Officer,
President, Chief Financial Officer, Secretary or one of its Assistant
Secretaries. Any such signature may be manual or facsimile.

         Securities bearing the manual or facsimile signature of individuals who
were at any time the proper officers of the Company shall bind the Company,
notwithstanding that such individuals or any of them have ceased to hold such
offices prior to the authentication and delivery of such Securities or did not
hold such offices at the date of such Securities.

         At any time and from time to time after the execution and delivery of
this Indenture, the Company may deliver Securities executed by the Company to
the Trustee or to its order for authentication, together with a Company Order
for the authentication and delivery of such Securities, and the Trustee in
accordance with such Company Order shall authenticate and make available for
delivery such Securities as in this Indenture provided and not otherwise.

         Each Security shall be dated the date of its authentication.

         No Security shall be entitled to any benefit under this Indenture or be
valid or obligatory for any purpose unless there appears on such Security a
certificate of authentication substantially in the form provided for herein
executed by the Trustee by manual signature of an authorized signatory, and such
certificate upon any Security shall be conclusive evidence, and the only
evidence, that such Security has been duly authenticated and delivered
hereunder.

         SECTION 3.4 GLOBAL SECURITIES; NON-GLOBAL SECURITIES; BOOK-ENTRY
PROVISIONS.

         (1) Global Securities

                 (i) Each Global Security authenticated under this Indenture
         shall be registered in the name of the Depositary designated by the
         Company for such Global Security or a nominee thereof and delivered to
         such Depositary or a nominee thereof or custodian therefor, and each
         such Global Security shall constitute a single Security for all
         purposes of this Indenture.

                 (ii) Except for exchanges of Global Securities for definitive,
         Non-global Securities at the sole discretion of the Company, no Global
         Security may be exchanged in

                                      -32-


<PAGE>


         whole or in part for Securities registered, and no transfer of a Global
         Security in whole or in part may be registered, in the name of any
         Person other than the Depositary for such Global Security or a nominee
         thereof unless (A) such Depositary (i) has notified the Company that it
         is unwilling or unable to continue as Depositary for such Global
         Security or (ii) has ceased to be a clearing agency registered as such
         under the Exchange Act or announces an intention permanently to cease
         business or does in fact do so or (B) there shall have occurred and be
         continuing an Event of Default with respect to such Global Security. In
         such event, if a successor Depositary for such Global Security is not
         appointed by the Company within 90 days after the Company receives such
         notice or becomes aware of such ineligibility, the Company will
         execute, and the Trustee, upon receipt of an Officers' Certificate
         directing the authentication and delivery of Securities, will
         authenticate and deliver, Securities, in any authorized denominations
         in an aggregate principal amount equal to the principal amount of such
         Global Security in exchange for such Global Security.

                 (iii) If any Global Security is to be exchanged for other
         Securities or canceled in whole, it shall be surrendered by or on
         behalf of the Depositary or its nominee to the Trustee, as Security
         Registrar, for exchange or cancellation, as provided in this Article
         III. If any Global Security is to be exchanged for other Securities or
         canceled in part, or if another Security is to be exchanged in whole or
         in part for a beneficial interest in any Global Security, in each case,
         as provided in Section 3.5, then either (A) such Global Security shall
         be so surrendered for exchange or cancellation, as provided in this
         Article III, or (B) the principal amount thereof shall be reduced or
         increased by an amount equal to the portion thereof to be so exchanged
         or canceled, or equal to the principal amount of such other Security to
         be so exchanged for a beneficial interest therein, as the case may be,
         by means of an appropriate adjustment made on the records of the
         Trustee, as Security Registrar, whereupon the Trustee, in accordance
         with the Applicable Procedures, shall instruct the Depositary or its
         authorized representative to make a corresponding adjustment to its
         records. Upon any such surrender or adjustment of a Global Security,
         the Trustee shall, subject to the provisions of Section 3.5 and as
         otherwise provided in this Article III, authenticate and deliver any
         Securities issuable in exchange for such Global Security (or any
         portion thereof) to or upon the order of, and registered in such names
         as may be directed by, the Depositary or its authorized representative.
         Upon the request of the Trustee in connection with the occurrence of
         any of the events specified in the preceding paragraph, the Company
         shall promptly make available to the Trustee a reasonable supply of
         Securities that are not in the form of Global Securities. The Trustee
         shall be entitled to rely upon any order, direction or request of the
         Depositary or its authorized representative which is given or made
         pursuant to this Article III if such order, direction or request is
         given or made in accordance with the Applicable Procedures.

                 (iv) Every Security authenticated and delivered upon 
         registration of transfer of, or in exchange for or in lieu of, a 
         Global Security or any portion thereof, whether pursuant to this 
         Article III or otherwise, shall be authenticated and delivered in the 
         form of, and shall be, a registered Global Security, unless such 
         Security is registered in the name of a Person other than the 
         Depositary for such Global

                                      -33-


<PAGE>


         Security or a nominee thereof, in which case such Security shall be
         authenticated and delivered in definitive, fully registered form,
         without interest coupons.

                 (v) The Depositary or its nominee, as registered owner of a 
         Global Security, shall be the Holder of such Global Security for all 
         purposes under the Indenture and the Securities, and owners of 
         beneficial interests in a Global Security shall hold such interests 
         pursuant to the Applicable Procedures. Accordingly, any such owner's 
         beneficial interest in a Global Security will be shown only on, and the
         transfer of such interest shall be effected only through, records 
         maintained by the Depositary or its nominee or its Agent Members and 
         such owners of beneficial interests in a Global Security will not be 
         considered the owners or holders thereof.

         (2) Pending the preparation of definitive Securities, the Company may
execute, and upon Company Order the Trustee shall authenticate and make
available for delivery, temporary Securities which are printed, lithographed,
typewritten, mimeographed or otherwise produced, in any authorized denomination,
substantially of the tenor of the definitive Securities in lieu of which they
are issued and with such appropriate insertions, omissions, substitutions and
other variations as the officers executing such Securities may determine, as
evidenced by their execution of such Securities. If temporary Securities are
issued, the Company will cause definitive Securities to be prepared without
unreasonable delay. After the preparation of definitive Securities, the
temporary Securities shall be exchangeable for definitive Securities upon
surrender of the temporary Securities at any office or agency of the Company
designated pursuant to Section 10.2, without charge to the Holder. Upon
surrender for cancellation of any one or more temporary Securities the Company
shall execute and the Trustee shall authenticate and make available for delivery
in exchange therefor a like principal amount of definitive Securities of
authorized denominations. Until so exchanged the temporary Securities shall in
all respects be entitled to the same benefits under this Indenture as definitive
Securities.

         SECTION 3.5 REGISTRATION; REGISTRATION OF TRANSFER AND EXCHANGE;
RESTRICTIONS ON TRANSFER.

         The Company shall cause to be kept at the Corporate Trust Office of the
Trustee a register (the register maintained in such office and in any other
office or agency of the Company designated pursuant to Section 10.2 being herein
sometimes collectively referred to as the "Security Register") in which, subject
to such reasonable regulations as it may prescribe, the Company shall provide
for the registration of Securities and of transfers of Securities. The Trustee
is hereby appointed "Security Registrar" for the purpose of registering
Securities and transfers and exchanges of Securities as herein provided.

         Upon surrender for registration of transfer of any Security at an
office or agency of the Company designated pursuant to Section 10.2 for such
purpose, the Company shall execute, and the Trustee shall authenticate and
deliver, in the name of the designated transferee or transferees, one or more
new Securities of any authorized denominations and of a like aggregate principal
amount and bearing such restrictive legends as may be required by this
Indenture.

                                      -34-


<PAGE>


         At the option of the Holder, and subject to the other provisions of
this Section 3.5, Securities may be exchanged for other Securities of any
authorized denomination and of a like aggregate principal amount, upon surrender
of the Securities to be exchanged at any such office or agency. Whenever any
Securities are so surrendered for exchange, and subject to the other provisions
of this Section 3.5, the Company shall execute, and the Trustee shall
authenticate and deliver, the Securities which the Holder making the exchange is
entitled to receive. Every Security presented or surrendered for registration of
transfer or for exchange shall (if so required by the Company or the Security
Registrar) be duly endorsed, or be accompanied by a written instrument of
transfer in form satisfactory to the Company, the Trustee and the Security
Registrar duly executed, by the Holder thereof or his attorney duly authorized
in writing. All Securities issued upon any registration of transfer or exchange
of Securities shall be the valid obligations of the Company, evidencing the same
debt and entitled to the same benefits under this Indenture as the Securities
surrendered upon such registration of transfer or exchange.

         No service charge shall be made to a Holder for any registration of
transfer or exchange of Securities except as provided in Section 3.6, but the
Company may require payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in connection with any registration of
transfer or exchange of Securities, other than exchanges pursuant to Section
3.4, 8.5[, 12.2](39) or 14.3 (other than where the shares of Common Stock are to
be issued or delivered in a name other than that of the Holder of the Security)
not involving any transfer and other than any stamp and other duties, if any,
which may be imposed in connection with any such transfer or exchange by the
United States or any political subdivision thereof or therein, which shall be
paid by the Company.

         Each Holder of a Security agrees to indemnify the Company and the 
Trustee against any liability that may result from the transfer, exchange or 
assignment of such Holder's Security in violation of any provision of this 
Indenture and/or applicable United States Federal or state securities law.

         The Trustee shall have no obligation or duty to monitor, determine 
or inquire as to compliance with any restrictions on transfer imposed under 
this Indenture or under applicable law with respect to any transfer of any 
interest in any Security (including any transfers between or among Depositary 
Participants or beneficial owners of interest in any Global Security) other 
than to require delivery of such certificates and other documentation or 
evidence as are expressly required by, and to do so if and when expressly 
required by the terms of, this Indenture, and to examine the same to 
determine substantial compliance as to form with the express requirements 
hereof.

         In the event of a redemption of the Securities, neither the Company nor
the Securities Registrar will be required (a) to register the transfer of or
exchange Securities for a period of 15 days immediately preceding the date
notice is given identifying the serial numbers of the Securities called for such
redemption or (b) to register the transfer of or exchange any Security, or
portion thereof, called for redemption.

         SECTION 3.6 MUTILATED, DESTROYED, LOST OR STOLEN SECURITIES.

         If any mutilated Security is surrendered to the Trustee, the Company
shall execute and the Trustee shall authenticate and deliver in exchange
therefor a new Security of like tenor and principal amount and bearing a number
not contemporaneously outstanding.

         If there shall be delivered to the Company and to the Trustee:

         (1) evidence to their satisfaction of the destruction, loss or theft of
any Security, and

----------

        (39) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -35-


<PAGE>


         (2) such security or indemnity as may be satisfactory to the Company
and the Trustee to save each of them and any agent of either of them harmless,
then, in the absence of actual notice to the Company or the Trustee that such
Security has been acquired by a bona fide purchaser, the Company shall execute
and the Trustee shall authenticate and deliver, in lieu of any such destroyed,
lost or stolen Security, a new Security of like tenor and principal amount and
bearing a number not contemporaneously outstanding.

         In case any such mutilated, destroyed, lost or stolen Security has
become or is about to become due and payable, the Company in its discretion [,
but subject to any conversion rights,](40) may, instead of issuing a new
Security, pay such Security, upon satisfaction of the conditions set forth in
the preceding paragraph.

         Upon the issuance of any new Security under this Section 3.6, the
Company may require the payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in relation thereto (other than any
stamp and other duties, if any, which may be imposed in connection therewith by
the United States or any political subdivision thereof or therein, which shall
be paid by the Company) and any other expenses (including the fees and expenses
of the Trustee) connected therewith.

         Every new Security issued pursuant to this Section 3.6 in lieu of any
mutilated, destroyed, lost or stolen Security shall constitute an original
additional contractual obligation of the Company, whether or not the mutilated,
destroyed, lost or stolen Security shall be at any time enforceable by anyone,
and such new Security shall be entitled to all the benefits of this Indenture
equally and proportionately with any and all other Securities duly issued
hereunder.

         The provisions of this Section 3.6 are exclusive and shall preclude (to
the extent lawful) all other rights and remedies of any Holder with respect to
the replacement or payment of mutilated, destroyed, lost or stolen Securities.

         SECTION 3.7 PAYMENT OF INTEREST; INTEREST RIGHTS PRESERVED.

         Interest on any Security which is payable, and is punctually paid or
duly provided for, on any Interest Payment Date shall be paid to the Person in
whose name that Security (or one or more Predecessor Securities) is registered
at the close of business on the Regular Record Date for such interest.

         Any interest on any Security which is payable, but is not punctually
paid or duly provided for, on any Interest Payment Date (herein called
"Defaulted Interest") shall forthwith cease to be payable to the Holder on the
relevant Regular Record Date by virtue of having been such Holder, and such

----------

        (40) INSERT IF SECURITIES ARE CONVERTIBLE


                                      -36-

<PAGE>


Defaulted Interest may be paid by the Company, at its election in each case, as
provided in clause (1) or (2) below:

         (1) The Company may elect to make payment of any Defaulted Interest to
the Persons in whose names the Securities (or their respective Predecessor
Securities) are registered at the close of business on a Special Record Date for
the payment of such Defaulted Interest, which shall be fixed in the following
manner. The Company shall notify the Trustee in writing of the amount of
Defaulted Interest proposed to be paid on each Security, the date of the
proposed payment and the Special Record Date, and at the same time the Company
shall deposit with the Trustee an amount of money equal to the aggregate amount
proposed to be paid in respect of such Defaulted Interest or shall make
arrangements satisfactory to the Trustee for such deposit prior to the date of
the proposed payment, such money when deposited to be held in trust for the
benefit of the Persons entitled to such Defaulted Interest as in this clause
provided. The Special Record Date for the payment of such Defaulted Interest
shall be not more than 15 days and not less than 10 days prior to the date of
the proposed payment and not less than 10 days after the receipt by the Trustee
of the notice of the proposed payment. The Trustee, in the name and at the
expense of the Company, shall cause notice of the proposed payment of such
Defaulted Interest and the Special Record Date therefor to be mailed,
first-class postage prepaid, to each Holder at such Holder's address as it
appears in the Security Register, not less than 10 days prior to such Special
Record Date. Notice of the proposed payment of such Defaulted Interest and the
Special Record Date therefor having been so mailed, such Defaulted Interest
shall be paid to the Persons in whose names the Securities (or their respective
Predecessor Securities) are registered at the close of business on such Special
Record Date and shall no longer be payable pursuant to the following clause (2).

         (2) The Company may make payment of any Defaulted Interest in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Securities may be listed, and upon such notice as may be required
by such exchange, if, after notice given by the Company to the Trustee of the
proposed payment pursuant to this clause, such manner of payment shall be deemed
practicable by the Trustee.

         Subject to the foregoing provisions of this Section and Section 3.5,
each Security delivered under this Indenture upon registration of transfer of or
in exchange for or in lieu of any other Security shall carry the rights to
interest accrued and unpaid, and to accrue, which were carried by such other
Security.

         [Interest on any Security which is converted in accordance with Section
12.2 during a Record Date Period shall be payable in accordance with the
provisions of Section 12.2.](41)

         SECTION 3.8 PERSONS DEEMED OWNERS.

         Prior to due presentment of a Security for registration of transfer,
the Company, the Trustee, any Paying Agent and any agent of the Company, the
Trustee or any Paying Agent may

----------

        (41) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -37-


<PAGE>

treat the Person in whose name such Security is registered as the owner of such
Security for the purpose of receiving payment of principal of, premium, if any,
and (subject to Section 3.7) interest on such Security and for all other
purposes whatsoever, whether or not such Security be overdue, and neither the
Company, the Trustee, any Paying Agent nor any agent of the Company, the Trustee
or any Paying Agent shall be affected by notice to the contrary.

         SECTION 3.9 CANCELLATION.

         All Securities surrendered for payment, redemption, repurchase,
registration of transfer or exchange [or conversion](42) or any Securities that
the Company may have acquired in any manner whatsoever, shall, if surrendered to
any Person other than the Trustee, be delivered to the Trustee. All Securities
so delivered to the Trustee shall be canceled promptly by the Trustee. No
Securities shall be authenticated in lieu of or in exchange for any Securities
canceled as provided in this Section 3.9. The Trustee shall dispose of all
canceled Securities in accordance with applicable law and its customary
practices in effect from time to time.

         SECTION 3.10 COMPUTATION OF INTEREST.

         Interest on the Securities shall be computed on the basis of a 360-day
year of twelve 30-day months.

         SECTION 3.11 CUSIP NUMBERS.

         The Company in issuing Securities may use "CUSIP" numbers (if then
generally in use) in addition to serial numbers; if so, the Trustee shall use
such CUSIP numbers in addition to serial numbers in notices of redemption and
repurchase as a convenience to Holders; provided that any such notice may state
that no representation is made as to the correctness of such CUSIP numbers
either as printed on the Securities or as contained in any notice of a
redemption or repurchase and that reliance may be placed only on the serial or
other identification numbers printed on the Securities, and any such redemption
or repurchase shall not be affected by any defect in or omission of such CUSIP
numbers. The Company will promptly notify the Trustee of any change in the 
CUSIP numbers.

                                   ARTICLE IV

                           SATISFACTION AND DISCHARGE

         SECTION 4.1 SATISFACTION AND DISCHARGE OF INDENTURE.

         This Indenture shall upon Company Request cease to be of further effect
(except as to any surviving rights of [conversion, or](43) registration of
transfer or exchange, or replacement of

----------

        (42) INSERT IF SECURITIES ARE CONVERTIBLE

        (43) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -38-


<PAGE>


Securities herein expressly provided for and the Company's obligations to the
Trustee pursuant to Section 6.7), and the Trustee, at the expense of the
Company, shall execute proper instruments in form and substance satisfactory to
the Trustee acknowledging satisfaction and discharge of this Indenture, when

         (1) either (i) all Securities theretofore authenticated and delivered
(other than (A) Securities which have been destroyed, lost or stolen and which
have been replaced or paid as provided in Section 3.6 and (B) Securities for
whose payment money has theretofore been deposited in trust or segregated and
held in trust by the Company and thereafter repaid to the Company or discharged
from such trust, as provided in Section 10.3) have been delivered to the Trustee
for cancellation; or (ii) all such Securities not theretofore delivered to the
Trustee or its agent for cancellation (other than Securities referred to in
clauses (A) and (B) of clause (1)(i) above) (a) have become due and payable, or
(b) will have become due and payable at their Stated Maturity within one year,
or (c) are to be called for redemption within one year under arrangements
satisfactory to the Trustee for the giving of notice of redemption by the
Trustee in the name, and at the expense, of the Company, and the Company, in the
case of clause (a), (b) or (c) above, has deposited or caused to be deposited
with the Trustee as trust funds (immediately available to the Holders in the
case of clause (a)) in trust for the purpose an amount in cash sufficient to pay
and discharge the entire indebtedness on such Securities not theretofore
delivered to the Trustee for cancellation, for principal, premium, if any, and
interest to the date of such deposit (in the case of Securities which have
become due and payable) or to the Stated Maturity or Redemption Date, as the
case may be;

         (2) the Company has paid or caused to be paid all other sums payable
hereunder by the Company; and

         (3) the Company has delivered to the Trustee an Officers' Certificate
and an Opinion of Counsel, each stating that all conditions precedent herein
provided for relating to the satisfaction and discharge of this Indenture have
been complied with.

         Notwithstanding the satisfaction and discharge of this Indenture, the
obligations of the Company to the Trustee under Section 6.7, the obligations of
the Company to any Authenticating Agent under Section 6.12, the obligations of
the Trustee under Section 4.2 and the last paragraph of Section 10.3 and the
obligations of the Company and the Trustee under Section 3.5 [and Article
XII](44) shall survive. Funds held in trust pursuant to this Section are not
subject to the provisions of Article XIII.

         SECTION 4.2 APPLICATION OF TRUST MONEY.

         Subject to the provisions of the last paragraph of Section 10.3, all
money deposited with the Trustee pursuant to Section 4.1 and in accordance with
the provisions of Article XIII shall be

----------

        (44) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -39-


<PAGE>


held in trust for the sole benefit of the Holders and not be subject to the
subordination provisions of Article XIII, and such monies shall be applied by
the Trustee, in accordance with the provisions of the Securities and this
Indenture, to the payment, either directly or through any Paying Agent
(including the Company acting as its own Paying Agent), to the Persons entitled
thereto, of the principal, premium, if any, and interest for whose payment such
money has been deposited with the Trustee.

         [All moneys deposited with the Trustee pursuant to Section 4.1 (and
held by it or any Paying Agent) for the payment of Securities subsequently
converted shall be returned to the Company upon Company Request.](45)

                                    ARTICLE V

                                    REMEDIES

         SECTION 5.1 EVENTS OF DEFAULT.

         "Event of Default", wherever used herein, means any one of the
following events (whatever the reason for such Event of Default and whether it
shall be occasioned by the provisions of Article XIII or be voluntary or
involuntary or be effected by operation of law or pursuant to any judgment,
decree or order of any court or any order, rule or regulation of any
administrative or governmental body):

         (1) default in the payment of the principal of or premium, if any, on
any Security at its Maturity, whether or not such payment is prohibited by the
subordination provisions of the Securities or of this Indenture; or

         (2) default in the payment of any interest upon any Security when it
becomes due and payable, and continuance of such default for a period of 30
days, whether or such payment is prohibited by the subordination provisions of
the Securities or of this Indenture; or

         (3) failure by the Company to give a Company Notice in accordance with
Section 14.3, whether or not such Company Notice is prohibited by the
subordination provisions of the Securities or of this Indenture; or

         (4) default in the performance, or breach, of any covenant or warranty
of the Company in this Indenture (other than a covenant or warranty a default in
the performance or breach of which is specifically dealt with elsewhere in this
Section), and continuance of such default or breach for a period of 60 days
after there has been given, by registered or certified mail, to the Company by
the Trustee or to the Company and the Trustee by the Holders of at least 25% in
principal amount of the Outstanding Securities a written notice specifying such

----------

        (45) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -40-


<PAGE>


default or breach and requiring it to be remedied and stating that such notice
is a "Notice of Default" hereunder; or

         (5) a default in the payment when due (whether at stated maturity or
any acceleration thereof) of the principal of, or acceleration of, any
indebtedness under any bonds, debentures, notes or other evidences of
indebtedness for money borrowed (or guarantee thereof) by the Company or any
Significant Subsidiary or under any mortgage, indenture or instrument under
which there may be issued or by which there may be secured or evidenced any
indebtedness for money borrowed by the Company or any Significant Subsidiary (an
"Instrument") with an aggregate principal amount then outstanding in excess of
U.S. $10,000,000, whether such indebtedness now exists or shall hereafter be
created if such indebtedness is not discharged, or such acceleration is not
rescinded or annulled, within a period of 30 days after there shall have been
given, by registered or certified mail, to the Company by the Trustee or to the
Company and the Trustee by the Holders of at least 25% in principal amount of
the Outstanding Securities a written notice specifying such default and
requiring the Company to cause such indebtedness to be discharged or cause such
default to be cured or waived or such acceleration to be rescinded or annulled
and stating that such notice is a "Notice of Default" hereunder; or

         (6) the entry by a court having jurisdiction in the premises of (A) a
decree or order for relief in respect of the Company or any Significant
Subsidiary in an involuntary case or proceeding under any applicable Federal or
State bankruptcy, insolvency, reorganization or other similar law or (B) a
decree or order adjudging the Company or any Significant Subsidiary a bankrupt
or insolvent, or approving as properly filed a petition seeking reorganization,
arrangement, adjustment or composition of or in respect of the Company or any
Significant Subsidiary under any applicable Federal or State law, or appointing
a custodian, receiver, liquidator, assignee, trustee, sequestrator or other
similar official of the Company or any Significant Subsidiary or of any
substantial part of the property of either, or ordering the winding up or
liquidation of its affairs, and the continuance of any such decree or order for
relief or any such other decree or order unstayed and in effect for a period of
60 consecutive days; or 

         (7) the commencement by the Company or any Significant Subsidiary of 
a voluntary case or proceeding under any applicable Federal or State 
bankruptcy, insolvency, reorganization or other similar law or of any other 
case or proceeding to be adjudicated a bankrupt or insolvent, or the consent 
by either to the entry of a decree or order for relief in respect of the 
Company or any Significant Subsidiary in an involuntary case or proceeding 
under any applicable Federal or State bankruptcy, insolvency, reorganization 
or other similar law or to the commencement of any bankruptcy or insolvency 
case or proceeding against either, or the filing by either of a petition or 
answer or consent seeking reorganization or similar relief under any 
applicable Federal or State law, or the consent by either to the filing of 
such petition or to the appointment of or taking possession by a custodian, 
receiver, liquidator, assignee, trustee, sequestrator or other similar 
official of the Company or any Significant Subsidiary or of any substantial 
part of the property of either, or the making by either of an assignment for 
the benefit of creditors, or the admission by either in writing of its 
inability to pay its debts generally as they become due, or the taking of 
corporate action by the Company or any Significant Subsidiary in furtherance 
of any such action.

                                      -41-


<PAGE>


         SECTION 5.2 ACCELERATION OF MATURITY; RESCISSION AND ANNULMENT.

         If an Event of Default (other than an Event of Default specified in
Section 5.1(6) or 5.1(7) with respect to the Company) occurs and is continuing,
then in every such case the Trustee or the Holders of not less than 25% in
principal amount of the Outstanding Securities may, subject to the provisions of
Article XIII, declare the principal of all the Securities to be due and payable
immediately, by a notice in writing to the Company (and to the Trustee if given
by the Holders), and upon any such declaration such principal amount and all
accrued interest thereon shall become immediately due and payable. If an Event
of Default specified in Section 5.1(6) or 5.1(7) with respect to the Company
occurs, the principal amount of, and accrued interest on, all the Securities
shall, subject to the provisions of Article XIII, ipso facto become immediately
due and payable without any declaration or other Act of the Holders or any act
on the part of the Trustee.

         At any time after such declaration of acceleration has been made and
before a judgment or decree for payment of the money due has been obtained by
the Trustee as hereinafter in this Article V provided, the Holders of a majority
in principal amount of the Outstanding Securities, by written notice to the
Company and the Trustee, may, on behalf of all Holders, rescind and annul such
declaration and its consequences if:

         (1) the Company has paid or deposited with the Trustee a sum sufficient
to pay

                 (i) all overdue interest on all Securities;

                 (ii) the principal of and premium, if any, on any Securities
         which have become due otherwise than by such declaration of
         acceleration and any interest thereon at the rate borne by the
         Securities;

                 (iii) to the extent permitted by applicable law, interest upon
         overdue interest at a rate of _____% per annum, and (iv) all sums paid
         or advanced by the Trustee hereunder and the reasonable compensation,
         expenses, disbursements and advances of the Trustee, its agents and its
         counsel;

         (2) all Events of Default, other than the nonpayment of the principal
of, and any premium and interest on, Securities which have become due solely by
such declaration of acceleration, have been cured or waived as provided in
Section 5.13; and

         (3) such rescission and annulment would not conflict with any judgment
or decree issued in appropriate judicial proceedings regarding the payment by
the Trustee to the Holders of the amounts referred to in 5.2(1).

         No rescission or annulment referred to above shall affect any
subsequent default or impair any right consequent thereon.

                                      -42-


<PAGE>


         SECTION 5.3 COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY
TRUSTEE.

         The Company covenants that if:

         (1) default is made in the payment of any interest on any Security when
it becomes due and payable and such default continues for a period of 30 days,
or

         (2) default is made in the payment of the principal of or premium, if
any, on any Security at the Maturity thereof,

the Company will, upon demand of the Trustee but subject to the provisions of
Article XIII pay to it, for the benefit of the Holders of such Securities the
whole amount then due and payable on such Securities for principal and interest
and interest on any overdue principal and premium, if any, and, to the extent
permitted by applicable law, on any overdue interest, at a rate of _____% per
annum, and in addition thereto, such further amount as shall be sufficient to
cover the reasonable costs and expenses of collection, including the reasonable
compensation, expenses, disbursements and advances of the Trustee, its agents
and its counsel.

         If the Company fails to pay such amounts forthwith upon such demand,
the Trustee, in its own name and as trustee of an express trust, may institute a
judicial proceeding for the collection of the sums so due and unpaid, may
prosecute such proceeding to judgment or final decree and may enforce the same
against the Company or any other obligor upon the Securities and collect the
moneys adjudged or decreed to be payable in the manner provided by law out of
the property of the Company or any other obligor upon the Securities, wherever
situated.

         If an Event of Default occurs and is continuing, the Trustee may in its
discretion proceed to protect and enforce its rights and the rights of the
Holders by such appropriate judicial proceedings as the Trustee shall deem most
effectual to protect and enforce any such rights, whether for the specific
enforcement of any covenant or agreement in this Indenture or in aid of the
Exercise of any power granted herein, or to enforce any other proper remedy.

         SECTION 5.4 TRUSTEE MAY FILE PROOFS OF CLAIM.

         In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relative to the Company or any other obligor upon the
Securities or the property of the Company or of such other obligor or the
creditors of either, the Trustee (irrespective of whether the principal of, and
any interest on, the Securities shall then be due and payable as therein
expressed or by declaration or otherwise and irrespective of whether the Trustee
shall have made any demand on the Company for the payment of overdue principal
or interest) shall be entitled and empowered, by intervention in such proceeding
or otherwise,

                                      -43-


<PAGE>


         (1) to file and prove a claim for the whole amount of principal,
premium, if any, and interest owing and unpaid in respect of the Securities and
take such other actions, including participating as a member, voting or
otherwise, of any official committee of creditors appointed in such matter, and
to file such other papers or documents, in each of the foregoing cases, as may
be necessary or advisable in order to have the claims of the Trustee (including
any claim for the reasonable compensation, expenses, disbursements and advances
of the Trustee, its agents and its counsel) and of the Holders allowed in such
judicial proceeding, and

         (2) to collect and receive any moneys or other property payable or
deliverable on any such claim and to distribute the same; and any custodian,
receiver, assignee, trustee, liquidator, sequestrator or other similar official
in any such judicial proceeding is hereby authorized by each Holder to make such
payments to the Trustee and, in the event that the Trustee shall consent to the
making of such payments directly to the Holders to pay to the Trustee any amount
due to it for the reasonable compensation, expenses, disbursements and advances
of the Trustee, its agents and its counsel and any other amounts due the Trustee
under Section 6.7.

         Nothing herein contained shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder any plan of
reorganization, arrangement, adjustment or composition affecting the Securities
or the rights of any Holder thereof or to authorize the Trustee to vote in
respect of the claim of any Holder in any such proceeding; provided, however,
that the Trustee may, on behalf of such Holders, vote for the election of a
trustee in bankruptcy or similar official.

         SECTION 5.5 TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF
SECURITIES.

         All rights of action and claims under this Indenture or the Securities
may be prosecuted and enforced by the Trustee without the possession of any of
the Securities or the production thereof in any proceeding relating thereto, and
any such proceeding instituted by the Trustee shall be brought in its own name
as trustee of an express trust, and any recovery of judgment shall, after
provision for the payment of the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and its counsel, be for
the ratable benefit of the Holders of the Securities in respect of which
judgment has been recovered.

         SECTION 5.6 APPLICATION OF MONEY COLLECTED.

         Subject to Article XIII, any money collected by the Trustee pursuant to
this Article V shall be applied in the following order, at the date or dates
fixed by the Trustee and, in case of the distribution of such money on account
of principal, premium, if any, or interest, upon presentation of the Securities
and the notation thereon of the payment if only partially paid and upon
surrender thereof if fully paid:

         FIRST: To the payment of all amounts due the Trustee under Section 6.7;

                                      -44-


<PAGE>


         SECOND: To the payment of the amounts then due and unpaid for principal
of, premium, if any, or interest on, the Securities in respect of which or for
the benefit of which such money has been collected, ratably, without preference
or priority of any kind, according to the amounts due and payable on such
Securities for principal, premium, if any, and interest, respectively;

         THIRD: To such other Person or Persons, if any, to the extent entitled
thereto; and

         FOURTH: Any remaining amounts shall be repaid to the Company.

         SECTION 5.7 LIMITATION ON SUITS.

         No Holder of any Security shall have any right to institute any
proceeding, judicial or otherwise, with respect to this Indenture, or for the
appointment of a receiver or trustee, or for any other remedy hereunder, unless:

         (1) such Holder has previously given written notice to the Trustee of a
continuing Event of Default;

         (2) the Holders of not less than 25% in principal amount of the
Outstanding Securities shall have made written request to the Trustee to
institute proceedings in respect of such Event of Default in its own name as
Trustee hereunder;

         (3) such Holder or Holders have offered to the Trustee indemnity 
reasonably satisfactory to the Trustee against the costs, expenses and 
liabilities to be incurred in compliance with such request;

         (4) the Trustee for 60 days after its receipt of such notice, request
and offer of indemnity has failed to institute any such proceeding; and

         (5) no direction inconsistent with such written request has been given
to the Trustee during such 60 day period by the Holders of a majority in
principal amount of the Outstanding Securities; it being understood and intended
that no one or more of such Holders shall have any right in any manner whatever
by virtue of, or by availing of, any provision of this Indenture to affect,
disturb or prejudice the rights of any other of such Holders, or to obtain or
seek to obtain priority or preference over any other of such Holders or to
enforce any right under this Indenture, except in the manner herein provided and
for the equal and ratable benefit of all such Holders.

                                      -45-


<PAGE>


         SECTION 5.8 UNCONDITIONAL RIGHT OF HOLDERS TO RECEIVE PRINCIPAL,
PREMIUM AND INTEREST [AND TO CONVERT.](46)

         Notwithstanding any other provision of this Indenture, but subject to
the provisions of Article XIII, the Holder of any Security shall have the right,
which is absolute and unconditional, to receive payment of the principal of,
premium, if any, and (subject to Section 3.7) interest on such Security on the
respective Stated Maturities expressed in such Security (or, in the case of
redemption or repurchase, on the Redemption Date or Repurchase Date, as the case
may be), [and to convert such Security in accordance with Article XII,](47) and
to institute suit for the enforcement of any such payment [and right to
convert](48), and such rights shall not be impaired without the consent of such
Holder.

         SECTION 5.9 RESTORATION OF RIGHTS AND REMEDIES.

         If the Trustee or any Holder has instituted any proceeding to enforce
any right or remedy under this Indenture and such proceeding has been
discontinued or abandoned for any reason, or has been determined adversely to
the Trustee or to such Holder, then and in every such case, subject to any
determination in such proceeding, the Company, the Trustee and the Holders shall
be restored severally and respectively to their former positions hereunder and
thereafter all rights and remedies of the Trustee and such Holders shall
continue as though no such proceeding had been instituted.

         SECTION 5.10 RIGHTS AND REMEDIES CUMULATIVE.

         Except as otherwise provided with respect to the replacement or payment
of mutilated, destroyed, lost or stolen Securities in the last paragraph of
Section 3.6, no right or remedy herein conferred upon or reserved to the Trustee
or to the Holders is intended to be exclusive of any other right or remedy, and
every right and remedy shall, to the extent permitted by law, be cumulative and
in addition to every other right and remedy given hereunder or now or hereafter
existing at law or in equity or otherwise. The assertion or employment of any
right or remedy hereunder, or otherwise, shall not prevent the concurrent
assertion or employment of any other appropriate right or remedy.

         SECTION 5.11 DELAY OR OMISSION NOT WAIVER.

         No delay or omission of the Trustee or of any Holder of any Security to
exercise any right or remedy accruing upon any Event of Default shall impair any
such right or remedy or constitute a waiver of any such Event of Default or any
acquiescence therein. Every right and remedy given by this Article V or by law
to the Trustee or to the Holders may be exercised from time to time, and as
often as may be deemed expedient, by the Trustee or (subject to the limitations
contained in this Indenture) by the Holders as the case may be.

----------

        (46) INSERT IF SECURITIES ARE CONVERTIBLE

        (47) INSERT IF SECURITIES ARE CONVERTIBLE

        (48) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -46-


<PAGE>


         SECTION 5.12 CONTROL BY HOLDERS.

         Subject to Section 6.3, the Holders of a majority in principal amount
of the Outstanding Securities shall have the right to direct the time, method
and place of conducting any proceeding for any remedy available to the Trustee
or exercising any trust or power conferred on the Trustee, provided that

         (1) such direction shall not be in conflict with any rule of law or
with this Indenture, and

         (2) the Trustee may take any other action deemed proper by the Trustee
which is not inconsistent with such direction.

         SECTION 5.13 WAIVER OF PAST DEFAULTS.

         The Holders, either (i) through the written consent of not less than a
majority in principal amount of the Outstanding Securities or (ii) by the
adoption of a resolution, at a meeting of Holders of the Outstanding Securities
at which a quorum is present, by the Holders of at least 66 2/3% in principal
amount of the Outstanding Securities represented at such meeting, may on behalf
of the Holders of all the Securities waive any past default hereunder and its
consequences, except a default (A) in the payment of the principal of, premium,
if any, or interest on any Security, or (B) in respect of a covenant or
provision hereof which under Article VIII cannot be modified or amended without
the consent of the Holder of each Outstanding Security affected.

         Upon any such waiver, such default shall cease to exist, and any Event
of Default arising therefrom shall be deemed to have been cured, for every
purpose of this Indenture; but no such waiver shall extend to any subsequent or
other default or impair any right consequent thereon.

         SECTION 5.14 UNDERTAKING FOR COSTS.

         All parties to this Indenture agree, and each Holder of any Security 
by his acceptance thereof shall be deemed to have agreed, that any court may 
in its discretion require, in any suit for the enforcement of any right or 
remedy under this Indenture, or in any suit against the Trustee for any 
action taken, suffered or omitted by it as Trustee, the filing by any party 
litigant in such suit of an undertaking to pay the costs of such suit, and 
that such court may in its discretion assess reasonable costs, including 
reasonable attorneys' fees and expenses, against any party litigant in such 
suit, having due regard to the merits and good faith of the claims or 
defenses made by such party litigant; but the provisions of this Section 5.14 
shall not apply to any suit instituted by the Company, to any suit instituted 
by the Trustee, to any suit instituted by any Holder, or group of Holders, 
holding in the aggregate more than 10% in principal amount of the Outstanding 
Securities, or to any suit instituted by any Holder of any Security for the 
enforcement of the payment of the principal of, premium, if any, or interest 
on any Security on or after the respective Stated Maturity or Maturities 
expressed in such Security (or, in the case of redemption or

                                      -47-


<PAGE>


repurchase, on or after the Redemption Date or Repurchase Date, as the case may
be) [or for the enforcement of the right to convert any Security in accordance
with Article XII.](49)

         SECTION 5.15 WAIVER OF STAY, USURY OR EXTENSION LAWS.

         The Company covenants (to the extent that it may lawfully do so) that
it will not at any time insist upon, or plead, or in any manner whatsoever claim
or take the benefit or advantage of, any stay, usury or extension law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture; and the Company (to the extent that it may
lawfully do so) hereby expressly waives all benefit or advantage of any such law
and covenants that it will not hinder, delay or impede by reason of such law the
execution of any power herein granted to the Trustee, but will suffer and permit
the execution of every such power as though no such law had been enacted.

                                   ARTICLE VI

                                   THE TRUSTEE

         SECTION 6.1 CERTAIN DUTIES AND RESPONSIBILITIES.

         (1) Except during the continuance of an Event of Default,

                 (i) the Trustee undertakes to perform such duties and only such
         duties as are specifically set forth in this Indenture, and no implied
         covenants or obligations shall be inferred or implied into this 
         Indenture against the Trustee; and

                 (ii) in the absence of bad faith on its part, the Trustee may
         conclusively rely, as to the truth of the statements and the
         correctness of the opinions expressed therein, upon certificates or
         opinions furnished to the Trustee and conforming to the requirements of
         this Indenture, but in the case of any such certificates or opinions
         which by any provision hereof are specifically required to be furnished
         to the Trustee, the Trustee shall be under a duty to examine the same
         to determine whether or not they conform to the requirements of this
         Indenture, but not to verify the contents thereof.

         (2) In case an Event of Default has occurred and is continuing, the
Trustee shall exercise such of the rights and powers vested in it by this
Indenture, and use the same degree of care and skill in their exercise, as a
prudent man would exercise or use under the circumstances in the conduct of his
own affairs.

----------

        (49) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -48-


<PAGE>


         (3) No provision of this Indenture shall be construed to relieve the
Trustee from liability for its own negligent action, its own negligent failure
to act, or its own willful misconduct, except that:

                 (i) this paragraph (3) shall not be construed to limit the
         effect of paragraph (1) of this Section;

                 (ii) the Trustee shall not be liable for any error of judgment
         made in good faith by a Responsible Officer, unless it shall be proved
         that the Trustee was negligent in ascertaining the pertinent facts;

                 (iii) the Trustee shall not be liable with respect to any
         action taken or omitted to be taken by it in good faith in accordance
         with the direction of the Holders of a majority in principal amount of
         the Outstanding Securities relating to the time, method and place of
         conducting any proceeding for any remedy available to the Trustee, or
         exercising any trust or power conferred upon the Trustee, under this
         Indenture; and

                 (iv) no provision of this Indenture shall require the Trustee
         to expend or risk its own funds or otherwise incur any financial
         liability in the performance of any of its duties hereunder, or in the
         exercise of any of its rights or powers, if it shall have reasonable
         grounds for believing that repayment of such funds or adequate
         indemnity against such risk or liability is not reasonably assured to
         it.

         (4) Whether or not therein expressly so provided, every provision of
this Indenture relating to the conduct or affecting the liability of or
affording protection to the Trustee shall be subject to the provisions of this
Section.

         SECTION 6.2 NOTICE OF DEFAULTS.

         Within 90 days after the occurrence of any default hereunder as to
which a Responsible Officer of the Trustee has received written notice, the
Trustee shall give to all Holders, in the manner provided in Section 1.6, notice
of such default, unless such default shall have been cured or waived; provided,
however, that, except in the case of a default in the payment of the principal
of, premium, if any, or interest on any Security the Trustee shall be protected
in withholding such notice if and so long as the board of directors, the
executive committee or a trust committee of directors or Responsible Officers of
the Trustee in good faith determines that the withholding of such notice is in
the interest of the Holders; and provided, further, that in the case of any
default of the character specified in Section 5.1(4), no such notice to Holders
shall be given until at least 60 days after the occurrence thereof or, if
applicable, the cure period specified therein. For the purpose of this Section,
the term "default" means any event which is, or after notice or lapse of time or
both would become, an Event of Default.

                                      -49-


<PAGE>


         SECTION 6.3 CERTAIN RIGHTS OF TRUSTEE.

         Subject to the provisions of Section 6.1:

         (1) the Trustee may conclusively rely, and shall be protected in 
acting or refraining from acting, upon any resolution, Officers' Certificate, 
other certificate, statement, instrument, opinion, report, notice, request, 
direction, consent, order, bond, debenture, note, coupon, other evidence of 
indebtedness or other paper or document (collectively, the "Documents") 
believed by it to be genuine and to have been signed or presented by the 
proper party or parties, and the Trustee need not investigate any fact or 
matter stated in such Documents;

         (2) any request or direction of the Company mentioned herein shall be
sufficiently evidenced by a Company Request or Company Order and any resolution
of the Board of Directors shall be sufficiently evidenced by a Board Resolution;

         (3) whenever in the administration of this Indenture the Trustee shall
deem it desirable that a matter be proved or established prior to taking,
suffering or omitting any action hereunder, the Trustee (unless other evidence
be herein specifically prescribed) may, in the absence of bad faith on its part,
conclusively rely upon an Officers' Certificate;

         (4) the Trustee may consult with counsel of its selection and the
advice of such counsel or any Opinion of Counsel shall be full and complete
authorization and protection in respect of any action taken, suffered or omitted
by it hereunder in good faith and in reliance thereon;

         (5) the Trustee shall be under no obligation to exercise any of the 
rights or powers vested in it by this Indenture at the request or direction 
of any of the Holders pursuant to this Indenture, unless such Holders shall 
have offered to the Trustee security or indemnity reasonably satisfactory to 
the Trustee against the costs, expenses and liabilities which might be 
incurred by it in compliance with such request or direction;

         (6) the Trustee shall not be bound to make any investigation into 
the facts or matters stated in any resolution, certificate, statement, 
instrument, opinion, report, notice, request, direction, consent, order, 
bond, debenture, note, coupon, other evidence of indebtedness or other paper 
or document, but the Trustee may make such further inquiry or investigation 
into such facts or matters as it may see fit, and, if the Trustee shall 
determine to make such further inquiry or investigation, it shall be entitled 
to examine the books, records and premises of the Company, personally or by 
agent or attorney and shall incur no liability or additional liability of any 
kind by reason of such inquiry or investigation; and Company shall reimburse 
the reasonable out-of-pocket costs actually incurred by the Trustee in 
connection with any such inquiry or investigation; 

         (7) the Trustee may execute any of the trusts or powers hereunder or
perform any duties hereunder either directly or by or through agents or
attorneys and the Trustee shall not be responsible for any misconduct or
negligence on the part of any agent or attorney appointed with due care by it
hereunder;

         (8) the Trustee shall not be liable for any action taken, suffered, 
or omitted to be taken by it in good faith and reasonably believed by it to 
be authorized or within the discretion or rights or powers conferred upon it 
by this Indenture;

         (9) the Trustee shall not be deemed to have notice of any Default or 
Event of Default unless a Responsible Officer of the Trustee has actual 
knowledge thereof or unless written notice of any event which is in fact such 
a default is received by the Trustee at the Corporate Trust Office of the 
Trustee, and such notice references the Securities and this Indenture;

         (10) the rights, privileges, protections, immunities and benefits 
given to the Trustee, including, without limitation, its right to be 
indemnified, are extended to, and shall be enforceable by, the Trustee in 
each of its capacities hereunder, and to each agent, custodian and other 
Person employed to act hereunder; and

         (11) the Trustee may request that the Company deliver an Officers' 
Certificate setting forth the names of individuals and/or titles of officers 
authorized at such time to take specified actions pursuant to this Indenture, 
which Officers' Certificate may be signed by any person authorized to sign an 
Officers' Certificate, including any person specified as so authorized in any 
such certificate previously delivered and not superseded.


                                      -50-



<PAGE>

        SECTION 6.4 NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF SECURITIES.

        The recitals contained herein and in the Securities (except the
Trustee's certificates of authentication) shall be taken as the statements of
the Company, and the Trustee assumes no responsibility for their correctness.
The Trustee makes no representations as to the validity or sufficiency of this
Indenture, of the Securities [or of the Common Stock issuable upon the
conversion of the Securities](50). The Trustee shall not be accountable for the
use or application by the Company of Securities or the proceeds thereof.

        SECTION 6.5 MAY HOLD SECURITIES, ACT AS TRUSTEE UNDER OTHER INDENTURES.

        The Trustee, any Authenticating Agent, any Paying Agent[, any Conversion
Agent](51) or any other agent of the Company or the Trustee, in its individual
or any other capacity, may become the owner or pledgee of Securities and may
otherwise deal with the Company with the same rights it would have if it were
not Trustee, Authenticating Agent, Paying Agent[, Conversion Agent](52) or such
other agent.

        The Trustee may become and act as trustee under other indentures under
which other securities, or certificates of interest or participation in other
securities, of the Company are outstanding in the same manner as if it were not
Trustee hereunder.

        SECTION 6.6 MONEY HELD IN TRUST.

        Money held by the Trustee in trust hereunder need not be segregated from
other funds except to the extent required by law. The Trustee shall be under no
liability for interest on any money received by it hereunder except as otherwise
agreed in writing with the Company.

        SECTION 6.7 COMPENSATION AND REIMBURSEMENT.

        The Company agrees:

        (1) to pay to the Trustee from time to time such reasonable compensation
as the Company and the Trustee shall from time to time agree in writing for all
services rendered by it hereunder (which compensation shall not be limited by
any provision of law in regard to the compensation of a trustee of an express
trust);

        (2) except as otherwise expressly provided herein, to reimburse the
Trustee upon its request for all reasonable expenses, disbursements and advances
incurred or made by the Trustee

----------

        (50) INSERT IF SECURITIES ARE CONVERTIBLE

        (51) INSERT IF SECURITIES ARE CONVERTIBLE

        (52) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -51-


<PAGE>

in accordance with any provision of this Indenture (including the reasonable
compensation and the expenses and disbursements of its agents and counsel),
except any such expense, disbursement or advance as may be attributable to its
negligence or bad faith; and

        (3) to indemnify the Trustee (and its directors, officers, employees 
and agents) for, and to hold it harmless against, any and all loss, 
liability, claim, damage or expense including taxes (other than taxes based 
on the income of the Trustee) incurred without negligence or bad faith on its 
part, arising out of or in connection with the acceptance or administration 
of this trust, including the reasonable costs, expenses and reasonable 
attorneys' fees of defending itself against any claim (whether asserted by 
the Company, any Holder or any other Person) or liability in connection with 
the exercise or performance of any of its powers or duties hereunder.

        When the Trustee incurs expenses or renders services in connection with
an Event of Default specified in Section 5.1(6) or Section 5.1(7), the expenses
(including the reasonable charges of its counsel) and the compensation for the
services are intended to constitute expenses of the administration under any
applicable Federal or state bankruptcy, insolvency or other similar law.

        The provisions of this Section shall survive the termination of this
Indenture or the earlier resignation or removal of the Trustee.

        SECTION 6.8 CORPORATE TRUSTEE REQUIRED; ELIGIBILITY.

        There shall at all times be a Trustee hereunder which shall be a Person
that is eligible pursuant to the Trust Indenture Act to act as such, having (or
being part of a holding company group with) a combined capital and surplus of at
least U.S. $50,000,000, subject to supervision or examination by federal or
state authority, and in good standing. The Trustee or an Affiliate of the
Trustee shall maintain an established place of business in the Borough of
Manhattan, The City of New York. If such corporation publishes reports of
condition at least annually, pursuant to law or to the requirements of said
supervising or examining authority, then for the purposes of this Section, the
combined capital and surplus of such corporation shall be deemed to be its
combined capital and surplus as set forth in its most recent report of condition
so published. If at any time the Trustee shall cease to be eligible in
accordance with the provisions of this Section, it shall resign immediately in
the manner and with the effect hereinafter specified in this Article and a
successor shall be appointed pursuant to Section 6.9.

        SECTION 6.9 RESIGNATION AND REMOVAL; APPOINTMENT OF SUCCESSOR.

        (1) No resignation or removal of the Trustee and no appointment of a
successor Trustee pursuant to this Article shall become effective until the
acceptance of appointment by the successor Trustee in accordance with the
applicable requirements of Section 6.10.

        (2) The Trustee may resign at any time by giving written notice thereof
to the Company. If the instrument of acceptance by a successor Trustee required
by Section 6.10 shall not have been delivered to the Trustee within 30 days
after the giving of such notice of

                                      -52-


<PAGE>


resignation, the resigning Trustee may petition any court of competent
jurisdiction for the appointment of a successor Trustee. The Company shall 
reimburse the reasonable out-of-pocket costs actually incurred by the Trustee 
in connection with any such opinion.

        (3) The Trustee may be removed at any time by an Act of the Holders 
of a majority in principal amount of the Outstanding Securities, delivered to 
the Trustee and the Company. If the instrument of acceptance by a successor 
Trustee required by Section 6.10 shall not have been delivered to the Trustee 
within 30 days after the giving of such notice of removal, the removed 
Trustee may petition any court of competent jurisdiction for the appointment 
of a successor Trustee. The Company shall reimburse the reasonable 
out-of-pocket costs actually incurred by the Trustee in connection with any 
such petition.

        (4) If at any time:

                (i) the Trustee shall cease to be eligible under Section 6.8 and
        shall fail to resign after written request therefor by the Company or by
        any Holder who has been a bona fide Holder for at least six months,

                (ii) the Trustee shall become incapable of acting or shall be
        adjudged a bankrupt or insolvent or a receiver of the Trustee or of its
        property shall be appointed or any public officer shall take charge or
        control of the Trustee or of its property or affairs for the purpose of
        rehabilitation, conservation or liquidation, or

                (iii) the Trustee shall fail to comply with the provisions of
        Section 6.13 after written request therefor by the Company or any Holder
        who has been a bona fide Holder for at least six months, then, in any
        such case (i) the Company by a Board Resolution may remove the Trustee,
        or (ii) subject to Section 5.14, any Holder who has been a bona fide
        Holder for at least six months may, on behalf of himself and all others
        similarly situated, petition any court of competent jurisdiction for the
        removal of the Trustee and the appointment of a successor Trustee.

        (5) If the Trustee shall resign, be removed or become incapable of
acting, or if a vacancy shall occur in the office of Trustee for any cause, the
Company, by a Board Resolution, shall promptly appoint a successor Trustee and
shall comply with the applicable requirements of this Section and Section 6.10.
If, within one year after such resignation, removal or incapability, or the
occurrence of such vacancy, a successor Trustee shall be appointed by Act of the
Holders of a majority in principal amount of the Outstanding Securities
delivered to the Company and the retiring Trustee, the successor Trustee so
appointed shall, forthwith upon its acceptance of such appointment in accordance
with the applicable requirements of Section 6.10, become the successor Trustee
and supersede the successor Trustee appointed by the Company. If no successor
Trustee shall have been so appointed by the Company or the Holders and accepted
appointment in the manner required by this Section and Section 6.10, any Holder
who has been a bona fide Holder for at least six months may, on behalf of
himself and all others similarly situated, petition any court of competent
jurisdiction for the appointment of a successor Trustee.

                                      -53-


<PAGE>



        (6) The Company shall give notice of each resignation and each removal
of the Trustee and each appointment of a successor Trustee to all Holders in the
manner provided in Section 1.6. Each notice shall include the name of the
successor Trustee and the address of its Corporate Trust Office.

        SECTION 6.10 ACCEPTANCE OF APPOINTMENT BY SUCCESSOR.

        Every successor Trustee appointed hereunder shall execute, acknowledge
and deliver to the Company and to the retiring Trustee an instrument accepting
such appointment, and thereupon the resignation or removal of the retiring
Trustee shall become effective and such successor Trustee, without any further
act, deed or conveyance, shall become vested with all the rights, powers, trusts
and duties of the retiring Trustee; but, on the request of the Company or the
successor Trustee, such retiring Trustee shall, upon payment of its charges,
execute and deliver an instrument transferring to such successor Trustee all the
rights, powers and trusts of the retiring Trustee and shall duly assign,
transfer and deliver to such successor Trustee all property and money held by
such retiring Trustee hereunder. Upon request of any such successor Trustee, the
Company shall execute any and all instruments for more fully and certainly
vesting in and confirming to such successor Trustee all such rights, powers and
trusts.

        No successor Trustee shall accept its appointment unless at the time of
such acceptance such successor Trustee shall be eligible under this Article.

        SECTION 6.11 MERGER, CONVERSION, CONSOLIDATION OR SUCCESSION TO
BUSINESS.

        Any corporation into which the Trustee may be merged or converted or
with which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to all or substantially all of the corporate trust
business of the Trustee (including the trust created by this Indenture), shall
be the successor of the Trustee hereunder, provided such corporation shall be
otherwise eligible under this Article, without the execution or filing of any
paper or any further act on the part of any of the parties hereto. In case any
Securities shall have been authenticated, but not delivered, by the Trustee then
in office, any successor by merger, conversion or consolidation to such
authenticating Trustee may adopt such authentication and deliver the Securities
so authenticated with the same effect as if such successor Trustee had itself
authenticated such Securities.

        SECTION 6.12 AUTHENTICATING AGENTS.

        The Trustee may, with the consent of the Company, appoint an
Authenticating Agent or Agents acceptable to the Company with respect to the
Securities which shall be authorized to act on behalf of the Trustee to
authenticate Securities issued upon original issue and upon registration of
transfer or redemption, exchange or substitution pursuant to this Indenture.
Securities authenticated by an Authenticating Agent shall be entitled to the
benefits of this Indenture and shall be valid and obligatory for all purposes as
if authenticated by the Trustee

                                      -54-


<PAGE>



hereunder, and every reference in this Indenture to the authentication and
delivery of Securities by the Trustee or the Trustee's certificate of
authentication shall be deemed to include authentication and delivery on behalf
of the Trustee by an Authenticating Agent and a certificate of authentication
executed on behalf of the Trustee by an Authenticating Agent. Each
Authenticating Agent shall be subject to acceptance by the Company and shall at
all times be a corporation organized and doing business under the laws of the
United States of America, any State thereof or the District of Columbia,
authorized under such laws to act as Authenticating Agent and subject to
supervision or examination by government or other fiscal authority. If at any
time an Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section 6.12, such Authenticating Agent shall resign
immediately in the manner and with the effect specified in this Section 6.12.

        Any corporation into which an Authenticating Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which such Authenticating Agent
shall be a party, or any corporation succeeding to the corporate agency or
corporate trust business of an Authenticating Agent, shall continue to be an
Authenticating Agent, provided such corporation shall be otherwise eligible
under this Section 6.12, without the execution or filing of any paper or any
further act on the part of the Trustee or the Authenticating Agent.

        An Authenticating Agent may resign at any time by giving written notice
thereof to the Trustee and to the Company. The Trustee may at any time terminate
the agency of an Authenticating Agent by giving written notice thereof to such
Authenticating Agent and to the Company. Upon receiving such a notice of
resignation or upon such a termination, or in case at any time such
Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section 6.12, the Trustee may appoint a successor
Authenticating Agent which shall be subject to acceptance by the Company. Any
successor Authenticating Agent upon acceptance of its appointment hereunder
shall become vested with all the rights, powers and duties of its predecessor
hereunder, with like effect as if originally named as an Authenticating Agent.
No successor Authenticating Agent shall be appointed unless eligible under the
provisions of this Section 6.12.

        The Company agrees to pay to each Authenticating Agent from time to time
reasonable compensation for its services under this Section 6.12.

        If an Authenticating Agent is appointed with respect to the Securities
pursuant to this Section 6.12, the Securities may have endorsed thereon, in
addition to or in lieu of the Trustee's certification of authentication, an
alternative certificate of authentication in the following form:

        This is one of the Securities referred to in the within-mentioned
Indenture.

                              __________________________________
                              as Trustee

                                      -55-


<PAGE>


                              By:_______________________________
                              As Authenticating Agent

                              By:_______________________________
                              Authorized Signatory

        SECTION 6.13 DISQUALIFICATION; CONFLICTING INTERESTS.

        If the Trustee has or shall acquire a conflicting interest within the
meaning of the Trust Indenture Act, the Trustee shall either eliminate such
interest or resign, to the extent and in the manner provided by, and subject to
the provisions of, the Trust Indenture Act and this Indenture.

        SECTION 6.14 PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY.

        If and when the Trustee shall be or become a creditor of the Company (or
any other obligor upon the Securities), the Trustee shall be subject to the
provisions of the Trust Indenture Act regarding the collection of claims against
the Company (or any such other obligor).

                                   ARTICLE VII

              CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

        SECTION 7.1 COMPANY MAY CONSOLIDATE, ETC., ONLY ON CERTAIN TERMS.

        The Company shall not consolidate with or merge into any other Person or
convey, transfer or lease all its properties and assets substantially as an
entirety to any Person, and the Company shall not permit any Person to
consolidate with or merge into the Company or convey, transfer, sell or lease
such Person's properties and assets substantially as an entirety to the Company
unless:

        (1) the Person formed by such consolidation or into or with which the
Company is merged or the Person to which the properties and assets of the
Company are so conveyed, transferred, sold or leased shall be a corporation,
limited liability company, partnership or trust organized and validly existing
under the laws of the United States of America, any State thereof or the
District of Columbia and, if other than the Company, shall expressly assume, by
an indenture supplemental hereto, executed and delivered to the Trustee, in form
satisfactory to the Trustee, the due and punctual payment of the principal of,
premium, if any, and interest on all of the Securities as applicable, and the
performance or observance of every covenant of this

                                      -56-


<PAGE>


Indenture on the part of the Company to be performed or observed [and shall have
provided for conversion rights in accordance with Article XII](53);

        (2) immediately after giving effect to such transaction, no Event of
Default, and no event that after notice or lapse of time or both, would become
an Event of Default, shall have occurred and be continuing; and

        (3) the Company has delivered to the Trustee an Officers' Certificate
and an Opinion of Counsel, each stating that such consolidation, merger,
conveyance, transfer or lease and, if a supplemental indenture is required in
connection with such transaction, such supplemental indenture comply with this
Article and that all conditions precedent herein provided for relating to such
transaction have been complied with, together with any documents required under
Section 8.3.

        SECTION 7.2 SUCCESSOR SUBSTITUTED.

        Upon any consolidation of the Company with, or merger of the Company
into any other Person or any conveyance, transfer or lease of all or
substantially all the properties and assets of the Company in accordance with
Section 7.1, the successor Person formed by such consolidation or into or with
which the Company is merged or to which such conveyance, transfer or lease is
made shall succeed to, and be substituted for, and may exercise every right and
power of, the Company under this Indenture with the same effect as if such
successor Person had been named as the Company herein, and thereafter, except in
the case of a lease, the predecessor Person shall be relieved of all obligations
and covenants under this Indenture and the Securities.

                                  ARTICLE VIII

                             SUPPLEMENTAL INDENTURES

         SECTION 8.1 SUPPLEMENTAL INDENTURES WITHOUT CONSENT OF HOLDERS.

        Without the consent of any Holders, the Company, when authorized by a 
Board Resolution, and the Trustee, at any time and from time to time, may 
enter into one or more indentures supplemental in form reasonably 
satisfactory to the Trustee hereto for any of the following purposes:

        (1) to evidence the succession of another Person to the Company and the
assumption by any such successor of the covenants and obligations of the Company
herein and in the Securities as permitted by Article VII of this Indenture; or

----------

        (53) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -57-


<PAGE>


        (2) to add to the covenants of the Company for the benefit of the
Holders or to surrender any right or power herein conferred upon the Company; or

        (3) to secure the Securities; or

        (4) [to make provision with respect to the conversion rights of Holders
pursuant to Section 12.11 or](54) to make provision with respect to the 
repurchase rights of Holders pursuant to Section 14.5; or

        (5) to comply with the requirements of the Trust Indenture Act or the
rules and regulations of the Commission thereunder in order to effect or
maintain the qualification of this Indenture under the Trust Indenture Act, as
contemplated by this Indenture or otherwise; or

        (6) to evidence and provide for the acceptance of appointment hereunder
by a successor Trustee; or

        (7) subject to Section 13.12, to make any change in Article XIII that
would limit or terminate the benefits available to any holder of Senior Debt
under such Article; or

        (8) to cure any ambiguity, to correct or supplement any provision herein
which may be inconsistent with any other provision herein or which is otherwise
defective, or to make any other provisions with respect to matters or questions
arising under this Indenture as the Company and the Trustee may deem necessary
or desirable, provided such action pursuant to this clause (8) shall not
adversely affect the interests of the Holders in any material respect.

        Upon Company Request, accompanied by a Board Resolution authorizing the
execution of any such supplemental indenture, and subject to and upon receipt by
the Trustee of the documents described in Section 8.3 hereof, the Trustee shall
join with the Company in the execution of any supplemental indenture authorized
or permitted by the terms of this Indenture and to make any further appropriate
agreements and stipulations which may be therein contained.

        SECTION 8.2 SUPPLEMENTAL INDENTURES WITH CONSENT OF HOLDERS.

        With either (i) the written consent of the Holders of not less than a
majority in principal amount of the Outstanding Securities, by the Act of said
Holders delivered to the Company and the Trustee, or (ii) by the adoption of a
resolution, at a meeting of Holders of the Outstanding Securities at which a
quorum is present, by the Holders of at least ______% in principal amount of the
Outstanding Securities represented at such meeting, the Company, when authorized
by a Board Resolution, and the Trustee may enter into an indenture or indentures
supplemental hereto for the purpose of adding any provisions to or changing in
any manner or eliminating any of the provisions of this Indenture or of
modifying in any manner the rights of the Holders under this

----------

        (54) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -58-


<PAGE>


Indenture; provided, however, that no such supplemental indenture shall, without
the consent or affirmative vote of the Holder of each Outstanding Security
affected thereby,

        (1) change the Stated Maturity of the principal of, or any installment
of interest on, any Security, or reduce the principal amount of, or the premium,
if any, or the rate of interest payable thereon, or reduce the amount payable
upon a redemption or mandatory repurchase, or change the coin or currency of
payment of the principal of, premium, if any, or interest on any Security
(including any payment of the Redemption Price or Repurchase Price in respect of
such Security) or impair the right to institute suit for the enforcement of any
payment in respect of any Security on or after the Stated Maturity thereof (or,
in the case of redemption or any repurchase, on or after the Redemption Date or
Repurchase Date, as the case may be) [or, except as permitted by Section 12.11,
adversely affect the right of Holders to convert any Security as provided in
Article XII,](55) or modify the provisions of this Indenture with respect to the
subordination of the Securities in a manner adverse to the Holders; or

        (2) reduce the requirements of Section 9.4 for quorum or voting, or
reduce the percentage in principal amount of the Outstanding Securities the
consent of whose Holders is required for any such supplemental indenture or the
consent of whose Holders is required for any waiver (of compliance with certain
provisions of this Indenture or certain defaults hereunder and their
consequences) provided for in this Indenture; or

        (3) modify the obligation of the Company to maintain an office or agency
in the Borough of Manhattan, The City of New York, pursuant to Section 10.2; or

        (4) modify any of the provisions of this Section or Section 5.13, except
to increase any percentage contained herein or therein or to provide that
certain other provisions of this Indenture cannot be modified or waived without
the consent of the Holder of each Outstanding Security affected thereby; or

        (5) modify the provisions of Article XIV in a manner adverse to the
Holders.

        It shall not be necessary for any Act of Holders under this Section to
approve the particular form of any proposed supplemental indenture, but it shall
be sufficient if such Act shall approve the substance thereof.

        SECTION 8.3 EXECUTION OF SUPPLEMENTAL INDENTURES.

        In executing, or accepting the additional trusts created by, any 
supplemental indenture permitted by this Article or the modifications thereby 
of the trusts created by this Indenture, the Trustee shall be entitled to 
receive, and (subject to Sections 6.1 and 6.3) shall be fully protected in 
relying upon, an Opinion of Counsel and Officers' Certificate stating that 
the execution of such supplemental indenture

----------

        (55) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -59-


<PAGE>


is authorized or permitted by this Indenture, and that such supplemental
indenture has been duly authorized, executed and delivered by the Company and
constitutes a valid and legally binding obligation of the Company enforceable
against the Company in accordance with its terms. The Trustee may, but shall not
be obligated to, enter into any such supplemental indenture which affects the
Trustee's own rights, duties or immunities under this Indenture or otherwise.

        SECTION 8.4 EFFECT OF SUPPLEMENTAL INDENTURES.

        Upon the execution of any supplemental indenture under this Article,
this Indenture shall be modified in accordance therewith, and such supplemental
indenture shall form a part of this Indenture for all purposes; and every Holder
theretofore or thereafter authenticated and delivered hereunder appertaining
thereto shall be bound thereby.

        SECTION 8.5 REFERENCE IN SECURITIES TO SUPPLEMENTAL INDENTURES.

        Securities authenticated and delivered after the execution of any
supplemental indenture pursuant to this Article may, and shall if required by
the Trustee, bear a notation in form approved by the Trustee as to any matter
provided for in such supplemental indenture. If the Company shall so determine,
new Securities so modified as to conform, in the opinion of the Company and the
Trustee, to any such supplemental indenture may be prepared and executed by the
Company and authenticated and delivered by the Trustee in exchange for
Outstanding Securities.

        SECTION 8.6 NOTICE OF SUPPLEMENTAL INDENTURES.

        Promptly after the execution by the Company and the Trustee of any
supplemental indenture pursuant to the provisions of Section 8.2, the Company
shall give notice to all Holders of such fact, setting forth in general terms
the substance of such supplemental indenture, in the manner provided in Section
1.6. Any failure of the Company to give such notice, or any defect therein,
shall not in any way impair or affect the validity of any such supplemental
indenture.

                                   ARTICLE IX

                               MEETINGS OF HOLDERS

             SECTION 9.1 PURPOSES FOR WHICH MEETINGS MAY BE CALLED.

        A meeting of Holders may be called at any time and from time to time
pursuant to this Article to make, give or take any request, demand,
authorization, direction, notice, consent, waiver or other action provided by
this Indenture to be made, given or taken by Holders.

                                      -60-


<PAGE>


        SECTION 9.2 CALL, NOTICE AND PLACE OF MEETINGS.

        (1) The Trustee may at any time call a meeting of Holders for any
purpose specified in Section 9.1, to be held at such time and at such place in
the Borough of Manhattan, The City of New York, as the Trustee shall determine.
Notice of every meeting of Holders, setting forth the time and the place of such
meeting and in general terms the action proposed to be taken at such meeting,
shall be given, in the manner provided in Section 1.6, not less than 21 nor more
than 180 days prior to the date fixed for the meeting.

        (2) In case at any time the Company, pursuant to a Board Resolution, or
the Holders of at least 10% in principal amount of the Outstanding Securities
shall have requested the Trustee to call a meeting of the Holders for any
purpose specified in Section 9.1, by written request setting forth in reasonable
detail the action proposed to be taken at the meeting, and the Trustee shall not
have mailed the notice of such meeting within 21 days after receipt of such
request or shall not thereafter proceed to cause the meeting to be held as
provided herein, then the Company or the Holders in the amount specified, as the
case may be, may determine the time and the place in the Borough of Manhattan,
The City of New York, for such meeting and may call such meeting for such
purposes by giving notice thereof as provided in paragraph (1) of this Section.

        SECTION 9.3 PERSONS ENTITLED TO VOTE AT MEETINGS.

        To be entitled to vote at any meeting of Holders, a Person shall be (i)
a Holder of one or more Outstanding Securities, or (ii) a Person appointed by an
instrument in writing as proxy for a Holder or Holders of one or more
Outstanding Securities by such Holder or Holders. The only Persons who shall be
entitled to be present or to speak at any meeting of Holders shall be the
Persons entitled to vote at such meeting and their counsel, any representatives
of the Trustee and its counsel and any representatives of the Company and its
counsel.

        SECTION 9.4 QUORUM; ACTION.

        The Persons entitled to vote a majority in principal amount of the
Outstanding Securities shall constitute a quorum. In the absence of a quorum
within 30 minutes of the time appointed for any such meeting, the meeting shall,
if convened at the request of Holders, be dissolved. In any other case, the
meeting may be adjourned for a period of not less than 10 days as determined by
the chairman of the meeting prior to the adjournment of such meeting. In the
absence of a quorum at any such adjourned meeting, such adjourned meeting may be
further adjourned for a period not less than 10 days as determined by the
chairman of the meeting prior to the adjournment of such adjourned meeting
(subject to repeated applications of this sentence). Notice of the reconvening
of any adjourned meeting shall be given as provided in Section 9.2(1), except
that such notice need be given only once not less than five days prior to the
date on which the meeting is scheduled to be reconvened. Notice of the
reconvening of an adjourned meeting shall state expressly the percentage of the
principal amount of the Outstanding Securities which shall constitute a quorum.

                                      -61-


<PAGE>



        Subject to the foregoing, at the reconvening of any meeting adjourned
for a lack of a quorum, the Persons entitled to vote 25% in principal amount of
the Outstanding Securities at the time shall constitute a quorum for the taking
of any action set forth in the notice of the original meeting.

        At a meeting or an adjourned meeting duly reconvened and at which a
quorum is present as aforesaid, any resolution and all matters (except as
limited by the proviso to Section 8.2 and except to the extent Section 10.12
requires a different vote) shall be effectively passed and decided if passed or
decided by the lesser of (i) the Holders of not less than a majority in
principal amount of Outstanding Securities and (ii) the Persons entitled to vote
not less than 66 2/3% in aggregate principal amount of Outstanding Securities
represented and entitled to vote at such meeting.

        Any resolution passed or decisions taken at any meeting of Holders duly
held in accordance with this Section shall be binding on all the Holders whether
or not present or represented at the meeting. The Trustee shall, in the name and
at the expense of the Company, notify all the Holders of any such resolutions or
decisions pursuant to Section 1.6.

        SECTION 9.5 DETERMINATION OF VOTING RIGHTS; CONDUCT AND ADJOURNMENT OF
MEETINGS.

        (1) The Trustee may make such reasonable regulations as it may deem
advisable for any meeting of Holders in regard to proof of the holding of
Securities and of the appointment of proxies and in regard to the appointment
and duties of inspectors of votes, the submission and examination of proxies,
certificates and other evidence of the right to vote, and such other matters
concerning the conduct of the meeting as it shall deem appropriate. Except as
otherwise permitted or required by any such regulations, the holding of
Securities shall be proved in the manner specified in Section 1.4 and the
appointment of any proxy shall be proved in the manner specified in Section 1.4
or by having the signature of the Person executing the proxy guaranteed by any
bank, broker or other eligible institution participating in a recognized
medallion signature guarantee program.

        (2) The Trustee shall, by an instrument in writing, appoint a temporary
chairman (which may be the Trustee) of the meeting, unless the meeting shall
have been called by the Company or by Holders as provided in Section 9.2(1), in
which case the Company or the Holders calling the meeting, as the case may be,
shall in like manner appoint a temporary chairman. A permanent chairman and a
permanent secretary of the meeting shall be elected by vote of the Persons
entitled to vote a majority in principal amount of the Outstanding Securities
represented at the meeting.

        (3) At any meeting, each Holder or proxy shall be entitled to one vote
for each U.S.$1,000 principal amount of Securities held or represented by him;
provided, however, that no vote shall be cast or counted at any meeting in
respect of any Security challenged as not

                                      -62-


<PAGE>


Outstanding and ruled by the chairman of the meeting to be not Outstanding. The
chairman of the meeting shall have no right to vote, except as a Holder or
proxy.

        (4) Any meeting of Holders duly called pursuant to Section 9.2 at which
a quorum is present may be adjourned from time to time by Persons entitled to
vote a majority in principal amount of the Outstanding Securities represented at
the meeting, and the meeting may be held as so adjourned without further notice.

        SECTION 9.6 COUNTING VOTES AND RECORDING ACTION OF MEETINGS.

        The vote upon any resolution submitted to any meeting of Holders shall
be by written ballots on which shall be subscribed the signatures of the Holders
or of their representatives by proxy and the principal amounts at Stated
Maturity and serial numbers of the Outstanding Securities held or represented by
them. The permanent chairman of the meeting shall appoint two inspectors of
votes who shall count all votes cast at the meeting for or against any
resolution and who shall make and file with the secretary of the meeting their
verified written reports in duplicate of all votes cast at the meeting. A
record, at least in duplicate, of the proceedings of each meeting of Holders
shall be prepared by the secretary of the meeting and there shall be attached to
said record the original reports of the inspectors of votes on any vote by
ballot taken thereat and affidavits by one or more Persons having knowledge of
the facts setting forth a copy of the notice of the meeting and showing that
said notice was given as provided in Section 9.2 and, if applicable, Section
9.4. Each copy shall be signed and verified by the affidavits of the permanent
chairman and secretary of the meeting and one such copy shall be delivered to
the Company and another to the Trustee to be preserved by the Trustee, the
latter to have attached thereto the ballots voted at the meeting. Any record so
signed and verified shall be conclusive evidence of the matters therein stated.

                                    ARTICLE X

                                    COVENANTS

            SECTION 10.1 PAYMENT OF PRINCIPAL, PREMIUM AND INTEREST.

        The Company covenants and agrees that it will duly and punctually pay 
or cause to be paid the principal of and premium, if any, and interest on the 
Securities in accordance with the terms of the Securities and this Indenture. 
The Company will deposit or cause to be deposited with the Trustee, no later 
than 10 a.m. New York time on the date of the Stated Maturity of any Security 
or no later than the opening of business on the due date for any installment 
of interest, all payments so due, which payments shall be in immediately 
available funds on the date of such Stated Maturity or due date, as the case 
may be.

                                      -63-


<PAGE>




        SECTION 10.2 MAINTENANCE OF OFFICES OR AGENCIES.

        The Company will maintain in the Borough of Manhattan, The City of New
York, an office or agency where the Securities may be surrendered for
registration of transfer or exchange or for presentation for payment or for
[conversion,](56) redemption or repurchase and where notices and demands to or
upon the Company in respect of the Securities and this Indenture may be served.
The Company will give prompt written notice to the Trustee of the location, and
any change in the location, of such office or agency not designated or appointed
by the Trustee. If at any time the Company shall fail to maintain any such
required office or agency or shall fail to furnish the Trustee with the address
thereof, such presentations, surrenders, notices and demands may be made or
served at the Corporate Trust Office or the office or agency of the Trustee in
the Borough of Manhattan, The City of New York.

        The Company may at any time and from time to time vary or terminate the
appointment of any such agent or appoint any additional agents for any or all of
such purposes; provided, however, that until all of the Securities have been
delivered to the Trustee for cancellation, or moneys sufficient to pay the
principal of, premium, if any, and interest on the Securities have been made
available for payment and either paid or returned to the Company pursuant to the
provisions of Section 10.3, the Company will maintain in the Borough of
Manhattan, The City of New York, an office or agency where Securities may be
presented or surrendered for payment [and conversion](57), which shall initially
be ___________________, where Securities may be surrendered for registration of
transfer or exchange and where notices and demands to or upon the Company in
respect of the Securities and this Indenture may be served. The Company will
give prompt written notice to the Trustee, and notice to the Holders in
accordance with Section 1.6, of the appointment or termination of any such
agents and of the location and any change in the location of any such office or
agency.

        The Company hereby initially designates the Trustee as Paying Agent,
Security Registrar [and Conversion Agent](58), and each of the Corporate Trust
Office of the Trustee and the office or agency of the Trustee in the Borough of
Manhattan, The City of New York, located at______,
___________________________attention:___________________________________________
as one such office or agency of the Company for each of the aforesaid purposes.

          SECTION 10.3 MONEY FOR SECURITY PAYMENTS TO BE HELD IN TRUST.

        If the Company shall act as its own Paying Agent, it will, on or before
each due date of the principal of, premium, if any, or interest on any of the
Securities, segregate and hold in trust for the benefit of the Persons entitled
thereto a sum sufficient to pay the principal, premium, if any, or interest so
becoming due until such sums shall be paid to such Persons or otherwise disposed
of as herein provided and the Company will promptly notify the Trustee of its
action or failure so to act.

----------

        (56) INSERT IF SECURITIES ARE CONVERTIBLE

        (57) INSERT IF SECURITIES ARE CONVERTIBLE

        (58) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -64-


<PAGE>


        Whenever the Company shall have one or more Paying Agents, it will, 
no later than 10 a.m. New York time on each due date of the principal of, 
premium, if any, or interest on any Securities, deposit with the Trustee a 
sum in funds immediately payable on the payment date sufficient to pay the 
principal, premium, if any, or interest so becoming due, such sum to be held 
for the benefit of the Persons entitled to such principal, premium, if any, 
or interest, and (unless such Paying Agent is the Trustee) the Company will 
promptly notify the Trustee of any failure so to act.

        The Company will cause each Paying Agent other than the Trustee to
execute and deliver to the Trustee an instrument in which such Paying Agent
shall agree with the Trustee, subject to the provisions of this Section, that
such Paying Agent will:

        (1) hold all sums held by it for the payment of the principal of,
premium, if any, or interest on Securities for the benefit of the Persons
entitled thereto until such sums shall be paid to such Persons or otherwise
disposed of as herein provided;

        (2) give the Trustee notice of any default by the Company (or any other
obligor upon the Securities) in the making of any payment of principal, premium,
if any, or interest; and

        (3) at any time during the continuance of any such default, upon the
written request of the Trustee, forthwith pay to the Trustee all sums so held by
such Paying Agent.

        Anything in this Section 10.3 to the contrary notwithstanding, the
Company may at any time, for the purpose of obtaining the satisfaction and
discharge of this Indenture or for any other purpose, pay, or by Company Order
direct any Paying Agent to pay, to the Trustee all sums held in trust by the
Company or such Paying Agent, such sums to be held by the Trustee upon the same
trusts as those upon which such sums were held by the Company or such Paying
Agent; and, upon such payment by any Paying Agent to the Trustee, such Paying
Agent shall be released from all further liability with respect to such money.

        Any money deposited with the Trustee or any Paying Agent, or then held
by the Company, in trust for the payment of the principal of, premium, if any,
or interest on any Security and remaining unclaimed for two years after such
principal, premium, if any, or interest has become due and payable shall be paid
to the Company on Company Request, or (if then held by the Company) shall be
discharged from such trust; and the Holder of such Security shall thereafter, as
an unsecured general creditor, look only to the Company for payment thereof, and
all liability of the Trustee or such Paying Agent with respect to such trust
money, and all liability of the Company as trustee thereof, shall thereupon
cease. The Company shall not be liable for any interest on the sums paid to it
pursuant to this paragraph and shall not be regarded as a trustee of such money.

                                      -65-


<PAGE>




        SECTION 10.4 EXISTENCE.

        Subject to Article VII, the Company will do or cause to be done all
things necessary to preserve and keep in full force and effect its existence,
rights (charter and statutory) and franchises; provided, however, that the
Company shall not be required to preserve any such right or franchise if the
Company shall determine that the preservation thereof is no longer desirable in
the conduct of the business of the Company and that the loss thereof is not
disadvantageous in any material respect to the Holders.

        SECTION 10.5 PAYMENT OF TAXES AND OTHER CLAIMS.

        The Company will pay or discharge, or cause to be paid or discharged,
before the same may become delinquent, (i) all taxes, assessments and
governmental charges levied or imposed upon the Company or any Significant
Subsidiary or upon the income, profits or property of the Company or any
Significant Subsidiary, (ii) all claims for labor, materials and supplies which,
if unpaid, might by law become a lien or charge upon the property of the Company
or any Significant Subsidiary, and (iii) all stamps and other duties, if any,
which may be imposed by the United States or any political subdivision thereof
or therein in connection with the issuance, transfer, exchange [or
conversion](59) of any Securities or with respect to this Indenture; provided,
however, that, in the case of clauses (i) and (ii), the Company shall not be
required to pay or discharge or cause to be paid or discharged any such tax,
assessment, charge or claim (A) if the failure to do so will not, in the
aggregate, have a material adverse impact on the Company, or (B) if the amount,
applicability or validity is being contested in good faith by appropriate
proceedings.

        [SECTION 10.6 REGISTRATION AND LISTING.

        The Company (i) will effect all registrations with, and obtain all
approvals by, all governmental authorities that may be necessary under any
United States Federal or state law (including the Securities Act, the Exchange
Act and state securities and Blue Sky laws) before the shares of Common Stock
issuable upon conversion of Securities are issued and delivered, and qualified
or listed as contemplated by clause (ii); and (ii) will qualify the shares of
Common Stock required to be issued and delivered upon conversion of Securities,
prior to such issuance or delivery, for quotation on the Nasdaq National Market
or, if the Common Stock is not then quoted on the Nasdaq National Market, list
the Common Stock on each national securities exchange or quotation system on
which outstanding Common Stock is listed or quoted at the time of such
delivery.](60)

----------

        (59) INSERT IF SECURITIES ARE CONVERTIBLE

        (60) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -66-


<PAGE>


        SECTION 10.7 STATEMENT BY OFFICERS AS TO DEFAULT.

        The Company shall deliver to the Trustee, within 120 days after the end
of each fiscal year of the Company ending after the date hereof, an Officers'
Certificate, stating whether or not to the best knowledge of the signers thereof
the Company is in default in the performance and observance of any of the terms,
provisions and conditions of this Indenture (without regard to any period of
grace or requirement of notice provided hereunder) and, if the Company shall be
in default, specifying all such defaults and the nature and status thereof of
which they may have knowledge.

        The Company will deliver to the Trustee, forthwith upon becoming aware
of any default or any Event of Default under the Indenture, an Officers'
Certificate specifying with particularity such default or Event of Default and
further stating what action the Company has taken, is taking or proposes to take
with respect thereto. For the purpose of this Section, the term "default" means
any event which is, or after notice or lapse of time or both would become, an
Event of Default.

        Any notice required to be given under this Section 10.7 shall be
delivered to the Trustee at its Corporate Trust Office.

        SECTION 10.8 WAIVER OF CERTAIN COVENANTS.

        The Company may omit in any particular instance to comply with any
covenant or condition set forth in Sections 10.4 (other than with respect to the
existence of the Company (subject to Article VII)) and 10.5, inclusive (other
than a covenant or condition which under Article VIII cannot be modified or
amended without the consent of the Holder of each Outstanding Security
affected), if before the time for such compliance the Holders shall, through the
written consent of, or the adoption of a resolution at a meeting of Holders of
the Outstanding Securities at which a quorum is present by, not less than a
majority in principal amount of the Outstanding Securities, either waive such
compliance in such instance or generally waive compliance with such covenant or
condition, but no such waiver shall extend to or affect such covenant or
condition except to the extent so expressly waived, and, until such waiver shall
become effective, the obligations of the Company and the duties of the Trustee
or any Paying [or Conversion](61) Agent in respect of any such covenant or
condition shall remain in full force and effect.

                                   ARTICLE XI

                            REDEMPTION OF SECURITIES

        SECTION 11.1 RIGHT OF REDEMPTION.

        The Securities may be redeemed in accordance with the provisions of the
form of Securities set forth in Section 2.2.

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        (61) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -67-


<PAGE>


        SECTION 11.2 APPLICABILITY OF ARTICLE.

        Redemption of Securities at the election of the Company or otherwise, as
permitted or required by any provision of the Securities or this Indenture,
shall be made in accordance with such provision and this Article XI.

        SECTION 11.3 ELECTION TO REDEEM; NOTICE TO TRUSTEE.

        The election of the Company to redeem any Securities shall be evidenced
by a Board Resolution. In case of any redemption at the election of the Company
of any of the Securities, the Company shall, at least 45 days prior to the
Redemption Date fixed by the Company (unless a shorter notice shall be
satisfactory to the Trustee), notify the Trustee in writing of such Redemption
Date.

        SECTION 11.4 SELECTION BY TRUSTEE OF SECURITIES TO BE REDEEMED.

        If less than all the Securities are to be redeemed, the particular
Securities to be redeemed shall be selected by the Trustee within three Business
Days after it receives the notice described in 11.3, from the Outstanding
Securities not previously called for redemption, by such method as the Trustee
may deem fair and appropriate.

        [If any Security selected for partial redemption is converted in part
before termination of the conversion right with respect to the portion of the
Security so selected, the converted portion of such Security shall be deemed (so
far as may be) to be the portion selected for redemption. Securities which have
been converted during a selection of Securities to be redeemed may be treated by
the Trustee as Outstanding for the purpose of such selection.](62) The Trustee
shall promptly notify the Company and each Security Registrar in writing of the
Securities selected for redemption and, in the case of any Securities selected
for partial redemption, the principal amount and certificate numbers thereof to
be redeemed.

        For all purposes of this Indenture, unless the context otherwise
requires, all provisions relating to the redemption of Securities shall relate,
in the case of any

        Securities redeemed or to be redeemed only in part, to the portion of
the principal amount of such Securities which has been or is to be redeemed.

----------

        (62) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -68-


<PAGE>


        SECTION 11.5 NOTICE OF REDEMPTION.

        Notice of redemption shall be given in the manner provided in Section
1.6 to the Holders to be redeemed not less than 30 nor more than 60 days prior
to the Redemption Date, and such notice shall be irrevocable.

        All notices of redemption shall include the CUSIP number and state:

        (1) the Redemption Date;

        (2) the Redemption Price, and accrued interest, if any, to the
Redemption Date;

        (3) if less than all Outstanding Securities are to be redeemed, the
aggregate principal amount of Securities to be redeemed and the aggregate
principal amount of Securities which will be outstanding after such partial
redemption;

        (4) that on the Redemption Date the Redemption Price, and accrued
interest, if any, to the Redemption Date, will become due and payable upon each
such Security to be redeemed, and that interest thereon shall cease to accrue on
and after said date;

        [(5) the Conversion Rate, the date on which the right to convert the
Securities to be redeemed will terminate and the places where such Securities
may be surrendered for conversion;](63) and

        (6) the place or places where such Securities are to be surrendered for
payment of the Redemption Price and accrued interest, if any, to the Redemption
Date.

        In case of a partial redemption, the notice shall specify the serial and
CUSIP numbers (if any) and the portions thereof called for redemption and that
transfers and exchanges may occur on or prior to the Redemption Date.

        Notice of redemption of Securities to be redeemed at the election of the
Company shall be given by the Company or, at the Company's written request, by
the Trustee in the name of and at the expense of the Company. Notice of
redemption of Securities to be redeemed at the election of the Company received
by the Trustee shall be given by the Trustee to each Paying Agent in the name of
and at the expense of the Company. Notice of redemption of the Securities to be
redeemed at the election of the Company shall also be given to one or more
nationally-recognized reporting institutions such as Bloomberg.

        SECTION 11.6 DEPOSIT OF REDEMPTION PRICE.

        Prior to 10 a.m. New York time on any Redemption Date, the Company 
shall deposit with the Trustee (or, if the Company is acting as its own 
Paying Agent, segregate and hold in trust as provided in

----------

        (63) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -69-


<PAGE>

Section 10.3) an amount of money (which shall be in immediately available funds
on such Redemption Date) sufficient to pay the Redemption Price of, and (except
if the Redemption Date shall be an Interest Payment Date) accrued interest to
the Redemption Date on, all the Securities which are to be redeemed on that date
[other than any Securities called for redemption on that date which have been
converted prior to the date of such deposit](64).

        [If any Security called for redemption is converted, any money deposited
with the Trustee or so segregated and held in trust for the redemption of such
Security shall (subject to any right of the Holder of such Security or any
Predecessor Security to receive interest as provided in the last paragraph of
Section 3.7) be paid to the Company on Company Request or, if then held by the
Company, shall be discharged from such trust.](65)

        SECTION 11.7 SECURITIES PAYABLE ON REDEMPTION DATE.

        Notice of redemption having been given as aforesaid, the Securities so
to be redeemed shall, on the Redemption Date, become due and payable at the
Redemption Price therein specified and from and after such date (unless the
Company shall default in the payment of the Redemption Price, including accrued
interest) such Securities shall cease to bear interest. Upon surrender of any
Security for redemption in accordance with said notice, such Security shall be
paid by the Company at the Redemption Price together with accrued and unpaid
interest to the Redemption Date; provided, however, that installments of
interest on Securities whose Stated Maturity is on or prior to the Redemption
Date shall be payable to the Holders of such Securities, or one or more
Predecessor Securities, registered as such on the relevant Record Date according
to their terms and the provisions of Section 3.7.

        If any Security called for redemption shall not be so paid upon
surrender thereof for redemption, the principal amount of, premium, if any, and,
to the extent permitted by applicable law, accrued interest on such Security
shall, until paid, bear interest from the Redemption Date at a rate of _____%
per annum [and such Security shall remain convertible](66) until the Redemption
Price of such Security (or portion thereof, as the case may be) shall have been
paid or duly provided for.

        Any Security which is to be redeemed only in part shall be surrendered
at the Corporate Trust Office or an office or agency of the Company designated
for that purpose pursuant to Section 10.2 (with, if the Company or the Trustee
so requires, due endorsement by, or a written instrument of transfer in form
satisfactory to the Company and the Trustee duly executed by, the Holder thereof
or his attorney duly authorized in writing), and the Company shall execute, and
the Trustee shall authenticate and make available for delivery to the Holder of
such Security

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        (64) INSERT IF SECURITIES ARE CONVERTIBLE

        (65) INSERT IF SECURITIES ARE CONVERTIBLE

        (66) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -70-


<PAGE>

without service charge, a new Security or Securities, of any authorized
denomination as requested by such Holder, in aggregate principal amount equal to
and in exchange for the unredeemed portion of the principal of the Security so
surrendered.

        [SECTION 11.8 CONVERSION ARRANGEMENT ON CALL FOR REDEMPTION.

        In connection with any redemption of Securities, the Company may 
arrange for the purchase and conversion of any Securities by an agreement 
with one or more investment bankers or other purchasers (the "Purchasers") to 
purchase such Securities by paying to the Trustee in trust for the Holders, 
on or before the Redemption Date, an amount not less than the applicable 
Redemption Price, together with interest accrued and unpaid to the Redemption 
Date, of such Securities. Notwithstanding anything to the contrary contained 
in this Article XI, the obligation of the Company to pay the Redemption 
Price, together with interest accrued and unpaid to the Redemption Date, 
shall be deemed to be satisfied and discharged to the extent such amount is 
so paid by such Purchasers. If such an agreement is entered into (a copy of 
which shall be filed with the Trustee prior to the close of business on the 
Business Day immediately prior to the Redemption Date), any Securities called 
for redemption that are not duly surrendered for conversion by the Holders 
thereof may, at the option of the Company, be deemed, to the fullest extent 
permitted by law, and consistent with any agreement or agreements with such 
Purchasers, to be acquired by such Purchasers from such Holders and 
(notwithstanding anything to the contrary contained in Article XII) 
surrendered by such Purchasers for conversion, all as of immediately prior to 
the close of business on the Redemption Date (and the right to convert any 
such Securities shall be extended through such time), subject to payment of 
the above amount as aforesaid. At the direction of the Company, the Trustee 
shall hold and dispose of any such amount paid to it by the Purchasers to the 
Holders in the same manner as it would monies deposited with it by the 
Company for the redemption of Securities. Without the Trustee's prior written 
consent, no arrangement between the Company and such Purchasers for the 
purchase and conversion of any Securities shall increase or otherwise affect 
any of the powers, duties, responsibilities or obligations of the Trustee as 
set forth in this Indenture, and the Company agrees to indemnify the Trustee 
from, and hold it harmless against, any and all loss, liability, claim, 
damage or expense arising out of or in connection with any such arrangement 
for the purchase and conversion of any Securities between the Company and 
such Purchasers, including the costs and expenses, including reasonable legal 
fees, incurred by the Trustee in the defense of any claim or liability 
arising out of or in connection with the exercise or performance of any of 
its powers, duties, responsibilities or obligations under this Indenture.](67)

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        (67) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -71-


<PAGE>


                                  [ARTICLE XII

                            CONVERSION OF SECURITIES

             SECTION 12.1 CONVERSION PRIVILEGE AND CONVERSION RATE.

        Subject to and upon compliance with the provisions of this Article, at
the option of the Holder thereof, any Security may be converted into fully paid
and nonassessable shares (calculated as to each conversion to the nearest
1/100th of a share) of Common Stock of the Company at the Conversion Rate,
determined as hereinafter provided, in effect at the time of conversion. Such
conversion right shall commence upon the original issuance date of the
Securities and expire at the close of business on the date of Maturity, subject,
in the case of conversion of any Global Security, to any Applicable Procedures.
In case a Security or portion thereof is called for redemption at the election
of the Company or the Holder thereof exercises his right to require the Company
to repurchase the Security, such conversion right in respect of the Security, or
portion thereof so called, shall expire at the close of business on the Business
Day immediately preceding the Redemption Date or the Repurchase Date, as the
case may be, unless the Company defaults in making the payment due upon
redemption or repurchase, as the case may be (in each case subject as aforesaid
to any Applicable Procedures with respect to any Global Security).

        The rate at which shares of Common Stock shall be delivered upon
conversion (herein called the "Conversion Rate") shall be initially ______
shares of Common Stock for each U.S. $1,000 principal amount of Securities. The
Conversion Rate shall be adjusted in certain instances as provided in this
Article XII.

        SECTION 12.2 EXERCISE OF CONVERSION PRIVILEGE.

        In order to exercise the conversion privilege, the Holder of any
Security to be converted shall surrender such Security, duly endorsed in blank,
at any office or agency of the Company maintained for that purpose pursuant to
Section 10.2, accompanied by a duly signed conversion notice substantially in
the form set forth in Section 2.4 stating that the Holder elects to convert such
Security or, if less than the entire principal amount thereof is to be
converted, the portion thereof to be converted. Each Security surrendered for
conversion (in whole or in part) during the Record Date Period shall (except in
the case of any Security or portion thereof which has been called for redemption
on a Redemption Date, or is repurchasable on a Repurchase Date, occurring, in
either case, within such Record Date Period and, as a result, the right to
convert would terminate in such period) be accompanied by payment in New York
Clearing House funds or other funds acceptable to the Company of an amount equal
to the interest payable on such Interest Payment Date on the principal amount of
such Security (or part thereof, as the case may be) being surrendered for
conversion. The interest so payable on such Interest Payment Date with respect
to any Security (or portion thereof, if applicable) which is surrendered for
conversion during the Record Date Period shall be paid to the Holder of such
Security as of such Regular Record Date in an amount equal to the interest that
would have been payable on such Security if

                                      -72-


<PAGE>


such Security had been converted as of the close of business on such Interest
Payment Date. Interest payable in respect of any Security surrendered for
conversion on or after an Interest Payment Date shall be paid to the Holder of
such Security as of the next preceding Regular Record Date, notwithstanding the
exercise of the right of conversion. Except as provided in this paragraph and
subject to the last paragraph of Section 3.7, no cash payment or adjustment
shall be made upon any conversion on account of any interest accrued from the
Interest Payment Date next preceding the conversion date, in respect of any
Security (or part thereof, as the case may be) surrendered for conversion, or on
account of any dividends on the Common Stock issued upon conversion. The
Company's delivery to the Holder of the number of shares of Common Stock (and
cash in lieu of fractions thereof, as provided in this Indenture) into which a
Security is convertible will be deemed to satisfy the Company's obligation to
pay the principal amount of the Security.

        Securities shall be deemed to have been converted immediately prior to
the close of business on the day of surrender of such Securities for conversion
in accordance with the foregoing provisions, and at such time the rights of the
Holders of such Securities as Holders shall cease, and the Person or Persons
entitled to receive the Common Stock issuable upon conversion shall be treated
for all purposes as the record holder or holders of such Common Stock at such
time. As promptly as practicable on or after the conversion date, the Company
shall issue and deliver to the Trustee, for delivery to the Holder, a
certificate or certificates for the number of full shares of Common Stock
issuable upon conversion, together with payment in lieu of any fraction of a
share, as provided in Section 12.3.

        In the case of any Security which is converted in part only, upon such
conversion the Company shall execute and the Trustee shall authenticate and
deliver to the Holder thereof, at the expense of the Company, a new Security or
Securities of authorized denominations in an aggregate principal amount equal to
the unconverted portion of the principal amount of such Security. A Security may
be converted in part, but only if the principal amount of such Security to be
converted is an integral multiple of U.S.$1,000 and the principal amount of such
security to remain Outstanding after such conversion is an integral multiple of
$1,000.

        SECTION 12.3 FRACTIONS OF SHARES.

        No fractional shares of Common Stock shall be issued upon conversion 
of any Security or Securities. If more than one Security shall be surrendered 
for conversion at one time by the same Holder, the number of full shares 
which shall be issuable upon conversion thereof shall be computed on the 
basis of the aggregate principal amount of the Securities (or specified 
portions thereof) so surrendered. Instead of any fractional share of Common 
Stock which would otherwise be issuable upon conversion of any Security or 
Securities (or specified portions thereof), the Company shall calculate and 
pay a cash adjustment in respect of such fraction (calculated to the nearest 
1/100th of a share) in an amount equal to the same fraction of the Closing 
Price Per Share at the close of business on the day of conversion.

                                      -73-


<PAGE>



        SECTION 12.4 ADJUSTMENT OF CONVERSION RATE.

        The Conversion Rate shall be subject to adjustments from time to time as
follows:

        (1) In case the Company shall pay or make a dividend or other
distribution on shares of any class of capital stock of the Company payable in
shares of Common Stock, the Conversion Rate in effect at the opening of business
on the day following the date fixed for the determination of stockholders
entitled to receive such dividend or other distribution shall be increased by
dividing such Conversion Rate by a fraction of which the numerator shall be the
number of shares of Common Stock outstanding at the close of business on the
date fixed for such determination and the denominator shall be the sum of such
number of shares and the total number of shares constituting such dividend or
other distribution, such increase to become effective immediately after the
opening of business on the day following the date fixed for such determination.
If, after any such date fixed for determination, any dividend or distribution is
not in fact paid, the Conversion Rate shall be immediately readjusted, effective
as of the date the Board of Directors determines not to pay such dividend or
distribution, to the Conversion Rate that would have been in effect if such
determination date had not been fixed. For the purposes of this paragraph (1),
the number of shares of Common Stock at any time outstanding shall not include
shares held in the treasury of the Company but shall include shares issuable in
respect of scrip certificates issued in lieu of fractions of shares of Common
Stock. The Company will not pay any dividend or make any distribution on shares
of Common Stock held in the treasury of the Company.

        (2) In case the Company shall issue rights, options or warrants to all
holders of its Common Stock entitling them to subscribe for or purchase shares
of Common Stock at a price per share less than the current market price per
share (determined as provided in paragraph (8) of this Section 12.4) of the
Common Stock on the date fixed for the determination of stockholders entitled to
receive such rights, options or warrants (other than any rights, options or
warrants that by their terms will also be issued to any Holder upon conversion
of a Security into shares of Common Stock without any action required by the
Company or any other Person), the Conversion Rate in effect at the opening of
business on the day following the date fixed for such determination shall be
increased by dividing such Conversion Rate by a fraction of which the numerator
shall be the number of shares of Common Stock outstanding at the close of
business on the date fixed for such determination plus the number of shares of
Common Stock which the aggregate of the offering price of the total number of
shares of Common Stock so offered for subscription or purchase would purchase at
such current market price and the denominator shall be the number of shares of
Common Stock outstanding at the close of business on the date fixed for such
determination plus the number of shares of Common Stock so offered for
subscription or purchase, such increase to become effective immediately after
the opening of business on the day following the date fixed for such
determination. If, after any such date fixed for determination, any such rights,
options or warrants are not in fact issued, or are not exercised prior to the
expiration thereof, the Conversion Rate shall be immediately readjusted,
effective as of the date such rights, options or warrants expire, or the date
the Board of Directors determines not to issue such rights, options or warrants,
to the Conversion Rate that would have been in

                                      -74-


<PAGE>


effect if the unexercised rights, options or warrants had never been granted or
such determination date had not been fixed, as the case may be. For the purposes
of this paragraph (2), the number of shares of Common Stock at any time
outstanding shall not include shares held in the treasury of the Company but
shall include shares issuable in respect of scrip certificates issued in lieu of
fractions of shares of Common Stock. The Company will not issue any rights,
options or warrants in respect of shares of Common Stock held in the treasury of
the Company.

        (3) In case the outstanding shares of Common Stock shall be subdivided
into a greater number of shares of Common Stock, the Conversion Rate in effect
at the opening of business on the day following the day upon which such
subdivision becomes effective shall be proportionately increased, and,
conversely, in case the outstanding shares of Common Stock shall be combined
into a smaller number of shares of Common Stock, the Conversion Rate in effect
at the opening of business on the day following the day upon which such
subdivision or combination becomes effective shall be proportionately reduced,
such increase or reduction, as the case may be, to become effective immediately
after the opening of business on the day following the day upon which such
subdivision or combination becomes effective.

        (4) In case the Company shall, by dividend or otherwise, distribute to
all holders of its Common Stock evidences of its indebtedness, shares of any
class of capital stock or other property (including cash or assets or
securities, but excluding (i) any rights, options or warrants referred to in
paragraph (2) of this Section, (ii) any dividend or distribution paid
exclusively in cash, (iii) any dividend or distribution referred to in paragraph
(1) of this Section and (iv) any mergers or consolidations to which Section
12.11 applies), the Conversion Rate shall be adjusted so that the same shall
equal the rate determined by dividing the Conversion Rate in effect immediately
prior to the close of business on the date fixed for the determination of
stockholders entitled to receive such distribution by a fraction of which the
numerator shall be the current market price per share (determined as provided in
paragraph (8) of this Section 12.4) of the Common Stock on the date fixed for
such determination less the then fair market value (as determined by the Board
of Directors, whose determination shall be conclusive and described in a Board
Resolution filed with the Trustee) of the portion of the assets, shares or
evidences of indebtedness so distributed applicable to one share of Common Stock
and the denominator shall be such current market price per share of the Common
Stock, such adjustment to become effective immediately prior to the opening of
business on the day following the date fixed for the determination of
stockholders entitled to receive such distribution. If, after any such date
fixed for determination, any such distribution is not in fact made, the
Conversion Rate shall be immediately readjusted, effective as of the date that
the Board of Directors determines not to make such distribution, to the
Conversion Rate that would have been in effect if such determination date had
not been fixed.

        (5) In case the Company shall, by dividend or otherwise, distribute to
all holders of its Common Stock cash (excluding any cash that is distributed as
part of a distribution referred to in paragraph (4) of this Section or cash
distributed upon a merger or consolidation to which Section 12.11 applies) in an
aggregate amount that, combined together with (I) the aggregate amount of any
other cash distributions to all holders of its Common Stock made exclusively in

                                      -75-


<PAGE>


cash within the 365-day period preceding the date of payment of such
distribution and in respect of which no adjustment pursuant to this paragraph
(5) has been made and (II) the aggregate of any cash plus the fair market value
(as determined by the Board of Directors, whose determination shall be
conclusive and described in a Board Resolution) of consideration payable in
respect of any tender offer by the Company or any of its Subsidiaries for all or
any portion of the Common Stock concluded within the 365-day period preceding
the date of payment of such distribution and in respect of which no adjustment
pursuant to paragraph (6) of this Section 12.4 has been made (the "combined cash
and tender amount") exceeds 10% of the product of the current market price per
share (determined as provided in paragraph (8) of this Section 12.4) of the
Common Stock on the date for the determination of holders of shares of Common
Stock entitled to receive such distribution times the number of shares of Common
Stock outstanding on such date (the "aggregate current market price"), then, and
in each such case, immediately after the close of business on such date for
determination, the Conversion Rate shall be adjusted so that the same shall
equal the rate determined by dividing the Conversion Rate in effect immediately
prior to the close of business on the date fixed for determination of the
stockholders entitled to receive such distribution by a fraction (i) the
numerator of which shall be equal to the current market price per share
(determined as provided in paragraph (8) of this Section) of the Common Stock on
the date fixed for such determination less an amount equal to the quotient of
(x) the excess of such combined cash and tender amount over such aggregate
current market price divided by (y) the number of shares of Common Stock
outstanding on such date for determination and (ii) the denominator of which
shall be equal to the current market price per share (determined as provided in
paragraph (8) of this Section 12.4) of the Common Stock on such date fixed for
determination.

        (6) In case a tender offer made by the Company or any Subsidiary for all
or any portion of the Common Stock shall expire and such tender offer (as
amended upon the expiration thereof) shall require the payment to stockholders
(based on the acceptance (up to any maximum specified in the terms of the tender
offer) of Purchased Shares (as defined below)) of an aggregate consideration
having a fair market value (as determined by the Board of Directors, whose
determination shall be conclusive and described in a Board Resolution) that
combined together with (I) the aggregate of the cash plus the fair market value
(as determined by the Board of Directors, whose determination shall be
conclusive and described in a Board Resolution), as of the expiration of such
tender offer, of consideration payable in respect of any other tender offer by
the Company or any Subsidiary for all or any portion of the Common Stock
expiring within the 365-day period preceding the expiration of such tender offer
and in respect of which no adjustment pursuant to this paragraph (6) has been
made and (II) the aggregate amount of any cash distributions to all holders of
the Common Stock within the 365-day period preceding the expiration of such
tender offer and in respect of which no adjustment pursuant to paragraph (5) of
this Section has been made (the "combined tender and cash amount") exceeds ___%
of the product of the current market price per share of the Common Stock
(determined as provided in paragraph (8) of this Section 12.4) as of the last
time (the "Expiration Time") tenders could have been made pursuant to such
tender offer (as it may be amended) times the number of shares of Common Stock
outstanding (including any tendered shares) as of the Expiration Time, then, and
in each such case, immediately prior to the opening of business on the day after
the date of the

                                      -76-


<PAGE>

Expiration Time, the Conversion Rate shall be adjusted so that the same shall
equal the rate determined by dividing the Conversion Rate immediately prior to
close of business on the date of the Expiration Time by a fraction (i) the
numerator of which shall be equal to (A) the product of (I) the current market
price per share of the Common Stock (determined as provided in paragraph (8) of
this Section 12.4) on the date of the Expiration Time multiplied by (II) the
number of shares of Common Stock outstanding (including any tendered shares) on
the Expiration Time less (B) the combined tender and cash amount, and (ii) the
denominator of which shall be equal to the product of (A) the current market
price per share of the Common Stock (determined as provided in paragraph (8) of
this Section 12.4) as of the Expiration Time multiplied by (B) the number of
shares of Common Stock outstanding (including any tendered shares) as of the
Expiration Time less the number of all shares validly tendered and not withdrawn
as of the Expiration Time (the shares deemed so accepted up to any such maximum,
being referred to as the "Purchased Shares").

        (7) The reclassification of Common Stock into securities other than
Common Stock (other than any reclassification upon a consolidation or merger to
which Section 12.11 applies) shall be deemed to involve (a) a distribution of
such securities other than Common Stock to all holders of Common Stock (and the
effective date of such reclassification shall be deemed to be "the date fixed
for the determination of stockholders entitled to receive such distribution" and
"the date fixed for such determination" within the meaning of paragraph (4) of
this Section), and (b) a subdivision or combination, as the case may be, of the
number of shares of Common Stock outstanding immediately prior to such
reclassification into the number of shares of Common Stock outstanding
immediately thereafter (and the effective date of such reclassification shall be
deemed to be "the day upon which such subdivision becomes effective" or "the day
upon which such combination becomes effective", as the case may be, and "the day
upon which such subdivision or combination becomes effective" within the meaning
of paragraph (3) of this Section 12.4).

        (8) For the purpose of any computation under paragraphs (2), (4), (5) or
(6) of this Section 12.4, the current market price per share of Common Stock on
any date shall be calculated by the Company and be deemed to be the average of
the daily Closing Prices Per Share for the five consecutive Trading Days
selected by the Company commencing not more than 10 Trading Days before, and
ending not later than the earlier of the day in question and the day before the
"ex" date with respect to the issuance or distribution requiring such
computation. For purposes of this paragraph, the term "'ex' date", when used
with respect to any issuance or distribution, means the first date on which the
Common Stock trades the regular way in the applicable securities market or on
the applicable securities exchange without the right to receive such issuance or
distribution.

        (9) No adjustment in the Conversion Rate shall be required unless such
adjustment (plus any adjustments not previously made by reason of this paragraph
(9)) would require an increase or decrease of at least one percent in such rate;
provided, however, that any adjustments which by reason of this paragraph (9)
are not required to be made shall be carried forward and

                                      -77-


<PAGE>


taken into account in any subsequent adjustment. All calculations under this
Article shall be made to the nearest cent or to the nearest one-hundredth of a
share, as the case may be.

        (10) The Company may in its sole discretion make such increases in the
Conversion Rate, for the remaining term of the Securities or any shorter term,
in addition to those required by paragraphs (1), (2), (3), (4), (5) and (6) of
this Section 12.4, as it considers to be advisable in order to avoid or diminish
any income tax liability to any holders of shares of Common Stock resulting from
any dividend or distribution of stock or issuance of rights or warrants to
purchase or subscribe for stock or from any event treated as such for income tax
purposes. The Company shall have the power to resolve any ambiguity or correct
any error in this paragraph (10) and its actions in so doing shall, absent
manifest error, be final and conclusive.

        (11) Notwithstanding the foregoing provisions of this Section, no
adjustment of the Conversion Rate shall be required to be made (a) upon the
issuance of shares of Common Stock pursuant to any present or future plan for
the reinvestment of dividends or (b) because of a tender or exchange offer of
the character described in Rule 13e-4(h)(5) under the Exchange Act or any
successor rule thereto.

        (12) To the extent permitted by applicable law, the Company from time to
time may increase the Conversion Rate by any amount for any period of time if
the period is at least twenty (20) days and the Board of Directors shall have
made a determination that such increase would be in the best interests of the
Company, which determination shall be conclusive; provided, however, that no
such increase shall be taken into account for purposes of determining whether
the Closing Price Per Share of the Common Stock equals or exceeds ____% of the
Conversion Price in connection with an event which would otherwise be a Change
of Control pursuant to Section 14.4. Whenever the Conversion Rate is increased
pursuant to the preceding sentence, the Company shall give notice of the
increase to the Holders in the manner provided in Section 1.6 at least fifteen
(15) days prior to the date the increased Conversion Rate takes effect, and such
notice shall state the increased Conversion Rate and the period during which it
will be in effect.

        SECTION 12.5 NOTICE OF ADJUSTMENTS OF CONVERSION RATE.

        Whenever the Conversion Rate is adjusted as herein provided:

        (1) the Company shall compute the adjusted Conversion Rate in accordance
with Section 12.4 and shall prepare a certificate signed by the Chief Financial
Officer of the Company setting forth the adjusted Conversion Rate and showing in
reasonable detail the facts upon which such adjustment is based, and such
certificate shall promptly be filed with the Trustee and with each Conversion
Agent; and

        (2) upon each such adjustment, a notice stating that the Conversion Rate
has been adjusted and setting forth the adjusted Conversion Rate shall be
required, and as soon as practicable after it is required, such notice shall be
provided by the Company to all Holders in accordance with Section 1.6.

                                      -78-


<PAGE>



        Neither the Trustee nor any Conversion Agent shall be under any duty or
responsibility with respect to any such certificate or the information and
calculations contained therein, except to exhibit the same to any Holder
desiring inspection thereof at its office during normal business hours, and
shall not be deemed to have knowledge of any adjustment in the Conversion Rate
unless and until a Responsible Officer of the Trustee shall have received such a
certificate. Until a Responsible Officer of the Trustee receives such a
certificate, the Trustee and each Conversion Agent may assume without inquiry
that the last Conversion Rate of which the Trustee has knowledge of remains in
effect.

        SECTION 12.6 NOTICE OF CERTAIN CORPORATE ACTION.

        In case:

        (1) the Company shall declare a dividend (or any other distribution) on
its Common Stock payable (i) otherwise than exclusively in cash or (ii)
exclusively in cash in an amount that would require any adjustment pursuant to
Section 12.4; or

        (2) the Company shall authorize the granting to all or substantially all
of the holders of its Common Stock of rights, options or warrants to subscribe
for or purchase any shares of capital stock of any class or of any other rights;
or

        (3) of any reclassification of the Common Stock, or of any
consolidation, merger or share exchange to which the Company is a party and for
which approval of any stockholders of the Company is required, or of the
conveyance, sale, transfer or lease of all or substantially all of the assets of
the Company; or

        (4) of the voluntary or involuntary dissolution, liquidation or winding
up of the Company; then the Company shall cause to be filed at each office or
agency maintained for the purpose of conversion of Securities pursuant to
Section 10.2, and shall cause to be provided to all Holders in accordance with
Section 1.6, at least 20 days (or 10 days in any case specified in clause (1) or
(2) above) prior to the applicable record or effective date hereinafter
specified, a notice stating (x) the date on which a record is to be taken for
the purpose of such dividend, distribution, rights, options or warrants, or, if
a record is not to be taken, the date as of which the holders of Common Stock of
record to be entitled to such dividend, distribution, rights, options or
warrants are to be determined or (y) the date on which such reclassification,
consolidation, merger, conveyance, transfer, sale, lease, dissolution,
liquidation or winding up is expected to become effective, and the date as of
which it is expected that holders of Common Stock of record shall be entitled to
exchange their shares of Common Stock for securities, cash or other property
deliverable upon such reclassification, consolidation, merger, conveyance,
transfer, sale, lease, dissolution, liquidation or winding up. Neither the
failure to give such notice or the notice referred to in the following paragraph
nor any defect therein shall affect the legality or validity of the proceedings
described in clauses (1) through (4) of this Section 12.6. If at the time the
Trustee shall not be the Conversion Agent, a copy of such notice shall also
forthwith be filed by

                                      -79-


<PAGE>


the Company with the Trustee. The Company shall cause to be filed at each office
or agency maintained for the purpose of conversion of Securities pursuant to
Section 10.2, and shall cause to be provided to all Holders in accordance with
Section 1.6, notice of any tender offer by the Company or any Subsidiary for all
or any portion of the Common Stock at or about the time that such notice of
tender offer is provided to the public generally.

        SECTION 12.7 COMPANY TO RESERVE COMMON STOCK.

        The Company shall at all times reserve and keep available, free from
preemptive rights, out of its authorized but unissued Common Stock, for the
purpose of effecting the conversion of Securities, the full number of shares of
Common Stock then issuable upon the conversion of all Outstanding Securities.

        SECTION 12.8 TAXES ON CONVERSIONS.

        Except as provided in the next sentence, the Company will pay any and
all taxes and duties that may be payable in respect of the issue or delivery of
shares of Common Stock on conversion of Securities pursuant hereto. The Company
shall not, however, be required to pay any tax or duty which may be payable in
respect of any transfer involved in the issue and delivery of shares of Common
Stock in a name other than that of the Holder of the Security or Securities to
be converted, and no such issue or delivery shall be made unless and until the
Person requesting such issue has paid to the Company the amount of any such tax
or duty, or has established to the satisfaction of the Company that such tax or
duty has been paid.

        SECTION 12.9 COVENANT AS TO COMMON STOCK.

        The Company agrees that all shares of Common Stock which may be
delivered upon conversion of Securities, upon such delivery, will have been duly
authorized and validly issued and will be fully paid and nonassessable and,
except as provided in Section 12.8, the Company will pay all taxes, liens and
charges with respect to the issue thereof.

        SECTION 12.10 CANCELLATION OF CONVERTED SECURITIES.

        All Securities delivered for conversion shall be delivered to the
Trustee or its agent to be canceled by or at the direction of the Trustee, which
shall dispose of the same as provided in Section 3.9.

        SECTION 12.11 PROVISION IN CASE OF CONSOLIDATION, MERGER OR SALE OF
ASSETS.

        In case of any consolidation or merger of the Company with or into any
other Person, any merger of another Person with or into the Company (other than
a merger which does not result in any reclassification, conversion, exchange or
cancellation of outstanding shares of Common Stock of the Company) or any
conveyance, sale, transfer or lease of all or substantially all of the

                                      -80-


<PAGE>


assets of the Company, the Person formed by such consolidation or resulting from
such merger or which acquires such assets, as the case may be, shall execute and
deliver to the Trustee a supplemental indenture providing that the Holder of
each Security then Outstanding shall have the right thereafter, during the
period such Security shall be convertible as specified in Section 12.1, to
convert such Security only into the kind and amount of securities, cash and
other property receivable upon such consolidation, merger, conveyance, sale,
transfer or lease by a holder of the number of shares of Common Stock of the
Company into which such Security might have been converted immediately prior to
such consolidation, merger, conveyance, sale, transfer or lease, assuming such
holder of Common Stock of the Company (i) is not (A) a Person with which the
Company consolidated or merged with or into or which merged into or with the
Company or to which such conveyance, sale, transfer or lease was made, as the
case may be (a "Constituent Person"), or (B) an Affiliate of a Constituent
Person and (ii) failed to exercise his rights of election, if any, as to the
kind or amount of securities, cash and other property receivable upon such
consolidation, merger, conveyance, sale, transfer or lease (provided that if the
kind or amount of securities, cash and other property receivable upon such
consolidation, merger, conveyance, sale, transfer, or lease is not the same for
each share of Common Stock of the Company held immediately prior to such
consolidation, merger, conveyance, sale, transfer or lease by others than a
Constituent Person or an Affiliate thereof and in respect of which such rights
of election shall not have been exercised ("Non-electing Share"), then for the
purpose of this Section 12.11 the kind and amount of securities, cash and other
property receivable upon such consolidation, merger, conveyance, sale, transfer
or lease by the holders of each Non-electing Share shall be deemed to be the
kind and amount so receivable per share by a plurality of the Non-electing
Shares). Such supplemental indenture shall provide for adjustments which, for
events subsequent to the effective date of such supplemental indenture, shall be
as nearly equivalent as may be practicable to the adjustments provided for in
this Article. The above provisions of this Section 12.11 shall similarly apply
to successive consolidations, mergers, conveyances, sales, transfers or leases.
Notice of the execution of such a supplemental indenture shall be given by the
Company to the Holder of each Security as provided in Section 1.6 promptly upon
such execution.

        Neither the Trustee nor any Conversion Agent shall be under any
responsibility to determine the correctness of any provisions contained in any
such supplemental indenture relating either to the kind or amount of shares of
stock or other securities or property or cash receivable by Holders upon the
conversion of their Securities after any such consolidation, merger, conveyance,
transfer, sale or lease or to any such adjustment, but may accept as conclusive
evidence of the correctness of any such provisions, and shall be protected in
relying upon, an Officers' Certificate or Opinion of Counsel with respect
thereto, which the Company shall cause to be furnished to the Trustee upon
request.

        SECTION 12.12 RIGHTS ISSUED IN RESPECT OF COMMON STOCK.

        Rights, options or warrants distributed by the Company to all holders of
Common Stock entitling the holders thereof to subscribe for or purchase shares
of the Company's capital stock

                                      -81-


<PAGE>


(either initially or under certain circumstances), which rights, options or
warrants, until the occurrence of a specified event or events ("Trigger Event"):

        (i) are deemed to be transferred with such shares of Common Stock,

        (ii) are not exercisable, and

        (iii) are also issued in respect of future issuances of Common Stock

shall not be deemed distributed for purposes of Section 12.4(2) until the
occurrence of the earliest Trigger Event. If such right, option or warrant is
subject to subsequent events, upon the occurrence of which such right, option or
warrant shall become exercisable to purchase different securities, evidences of
indebtedness or other assets or entitle the holder to purchase a different
number or amount of the foregoing or to purchase any of the foregoing at a
different purchase price, then the occurrence of each such event shall be deemed
to be the date of issuance and record date with respect to a new right, option
or warrant (and a termination or expiration of the existing right, option or
warrant without exercise by the holder thereof). In addition, in the event of
any distribution (or deemed distribution) of rights, options or warrants, or any
Trigger Event or other event (of the type described in the preceding sentence)
with respect thereto, that shall have resulted in an adjustment to the
Conversion Rate under Section 12.4(2), (1) in the case of any such rights,
options or warrants which shall all have been redeemed or repurchased without
exercise by any holders thereof, the Conversion Rate shall be readjusted upon
such final redemption or repurchase to give effect to such distribution or
Trigger Event, as the case may be, as though it were a cash distribution, equal
to the per share redemption or repurchase price received by a holder of Common
Stock with respect to such rights, options or warrants (assuming such holder had
retained such rights, options or warrants), made to all holders of Common Stock
as of the date of such redemption or repurchase, and (2) in the case of any such
rights, options or warrants all of which shall have expired without exercise by
any holder thereof, the Conversion Price shall be readjusted as if such issuance
had not occurred.

        SECTION 12.13 RESPONSIBILITY OF TRUSTEE FOR CONVERSION PROVISIONS.

        The Trustee, subject to the provisions of Section 6.1, and any
Conversion Agent shall not at any time be under any duty or responsibility to
any Holder to determine whether any facts exist which may require any adjustment
of the Conversion Rate, or with respect to the nature or extent of any such
adjustment when made, or with respect to the method employed, or herein or in
any supplemental indenture provided to be employed, in making the same, or
whether a supplemental indenture need be entered into. Neither the Trustee,
subject to the provisions of Section 6.1, nor any Conversion Agent shall be
accountable with respect to the validity or value (or the kind or amount) of any
Common Stock, or of any other securities or property or cash, which may at any
time be issued or delivered upon the conversion of any Security; and it or they
do not make any representation with respect thereto. Neither the Trustee,
subject to the provisions of Section 6.1, nor any Conversion Agent shall be
responsible for any failure of the

                                      -82-


<PAGE>



Company to make or calculate any cash payment or to issue, transfer or deliver
any shares of Common Stock or share certificates or other securities or property
or cash upon the surrender of any Security for the purpose of conversion; and
the Trustee, subject to the provisions of Section 6.1, and any Conversion Agent
shall not be responsible for any failure of the Company to comply with any of
the covenants of the Company contained in this Article.](68)

                                  ARTICLE XIII

                           SUBORDINATION OF SECURITIES

               SECTION 13.1 SECURITIES SUBORDINATE TO SENIOR DEBT.

        The Company covenants and agrees, and each Holder, by its acceptance
thereof, likewise covenants and agrees, that, to the extent and in the manner
hereinafter set forth in this Article (subject to the provisions of Article IV),
the indebtedness represented by the Securities and the payment of the principal
of, or premium (including any Make-Whole Payment), if any, or interest on, each
and all of the Securities (including, but not limited to, the Redemption Price
with respect to the Securities to be called for redemption in accordance with
Article XI or the Repurchase Price with respect to Securities submitted for
repurchase in accordance with Article XIV), are hereby expressly made
subordinate and subject in right of payment to the prior payment in full in cash
of all Senior Debt.

        SECTION 13.2 NO PAYMENT IN CERTAIN CIRCUMSTANCES, PAYMENT OVER OF
PROCEEDS UPON DISSOLUTION, ETC.

        No payment shall be made with respect to the principal of, or premium
(including any Make-Whole Payment), if any, or interest on the Securities
(including, but not limited to, the Redemption Price with respect to the
Securities to be called for redemption in accordance with Article XI or the
Repurchase Price with respect to Securities submitted for repurchase in
accordance with Article XIV) except payments and distributions made by the
Trustee as permitted by Section 13.9, if:

        (i) a default in the payment of principal, premium, if any, or interest
(including a default under any repurchase or redemption obligation) or other
amounts with respect to any Senior Debt occurs and is continuing (or, in the
case of Senior Debt for which there is a period of grace, in the event of such a
default that continues beyond the period of grace, if any, specified in the
instrument or lease evidencing such Senior Debt) unless and until such default
shall have been cured or waived or shall have ceased to exist; or

        (ii) any other event of default occurs and is continuing with respect to
Designated Senior Debt that then permits holders of such Designated Senior Debt
to accelerate its maturity

----------

        (68) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -83-


<PAGE>


and the Trustee receives a notice of the default (a "Payment Blockage Notice")
from a Representative or holder of Designated Senior Debt or the Company.

        If the Trustee receives any Payment Blockage Notice pursuant to clause
(ii) above, no subsequent Payment Blockage Notice shall be effective for
purposes of this Section unless and until (A) at least 365 days shall have
elapsed since the initial effectiveness of the immediately prior Payment
Blockage Notice, and (B) all scheduled payments of principal, premium (including
any Make-Whole Payment), if any, and interest on the Securities that have come
due have been paid in full in cash (or, at the election of the Company and to
the extent permitted by the Indenture, shares of Common Stock). No nonpayment
default that existed or was continuing on the date of delivery of any Payment
Blockage Notice to the Trustee shall be, or be made, the basis for a subsequent
Payment Blockage Notice.

        The Company may and shall resume payments on and distributions in
respect of the Securities upon the earlier of:

        (1) in the case of a default referred to in clause (i) above, the date
upon which the default is cured or waived or ceases to exist, or

        (2) in the case of a default referred to in clause (ii) above, the date
upon which the default is cured or waived or ceases to exist or 179 days pass
after notice is received if the maturity of such Designated Senior Debt has not
been accelerated, unless this Article XIII otherwise prohibits the payment or
distribution at the time of such payment or distribution.

        In the event of (a) any insolvency or bankruptcy case or proceeding, or
any receivership, liquidation, reorganization or other similar case or
proceeding in connection therewith, relative to the Company or to its creditors,
as such, or to its assets, or (b) any liquidation, dissolution or other winding
up of the Company, whether voluntary or involuntary and whether or not involving
insolvency or bankruptcy, or (c) any assignment for the benefit of creditors or
any other marshaling of assets and liabilities of the Company, then and in any
such event the holders of Senior Debt shall be entitled to receive payment in
full in cash of all amounts due or to become due on or in respect of all Senior
Debt before the Holders of the Securities are entitled to receive any payment on
account of principal of (or premium, including any Make-Whole Payment, if any)
or interest on the Securities or on account of the purchase, redemption or other
acquisition of Securities, and to that end the holders of Senior Debt shall be
entitled to receive, for application to the payment thereof, any payment or
distribution of any kind or character, whether in cash, property or securities,
which may be payable or deliverable in respect of the Securities in any such
case, proceeding, dissolution, liquidation or other winding up or event.

        In the event that, notwithstanding the foregoing provisions of this
Section, the Trustee or the Holder of any Security shall have received any
payment or distribution of assets of the Company of any kind or character,
whether in cash, securities or other property, before all Senior Debt is paid in
full in cash, then and in such event such payment or distribution shall be paid
over or delivered forthwith to the trustee in bankruptcy, receiver, liquidating
trustee, custodian,

                                      -84-


<PAGE>


assignee, agent or other Person making payment or distribution of assets of the
Company for application to the payment of all Senior Debt remaining unpaid, to
the extent necessary to pay all Senior Debt in full in cash, after giving effect
to any concurrent payment or distribution to or for the holders of Senior Debt.

        For purposes of this Article only, the words "cash, securities or other
property" shall not be deemed to include shares of capital stock of the Company
as reorganized or readjusted, or securities of the Company or any other
corporation provided for by a plan of reorganization or readjustment, which
shares of stock or securities are subordinated in right of payment to all then
outstanding Senior Debt to substantially the same extent as, or to a greater
extent than, the Securities are so subordinated as provided in this Article. The
consolidation of the Company with, or the merger of the Company into, another
Person or the liquidation or dissolution of the Company following the conveyance
or transfer of its properties and assets substantially as an entirety to another
Person upon the terms and conditions set forth in Article VII shall not be
deemed a dissolution, winding up, liquidation, reorganization, assignment for
the benefit of creditors or marshaling of assets and liabilities of the Company
for the purposes of this Section if the Person formed by such consolidation or
into which the Company is merged or which acquires by conveyance or transfer
such properties and assets substantially as an entirety, as the case may be,
shall, as a part of such consolidation, merger, conveyance or transfer, comply
with the conditions set forth in Article VII.

        In the event that, notwithstanding the foregoing, the Company shall make
any payment to the Trustee or the Holder of any Security prohibited by the
foregoing provisions of this Section, then and in such event such payment shall
be paid over and delivered forthwith to the Company, in the case of the Trustee,
or the Trustee, in the case of such Holder.

        SECTION 13.3 PRIOR PAYMENT TO SENIOR DEBT UPON ACCELERATION OF
SECURITIES.

        In the event of the acceleration of the Securities because of an Event
of Default, no payment or distribution shall be made to the Trustee or any
holder of Securities in respect of the principal of, premium (including any
Make-Whole Payment), if any, or interest on the Securities (including, but not
limited to, the Redemption Price with respect to the Securities called for
redemption in accordance with Article XI or the Repurchase Price with respect to
the Securities submitted for repurchase in accordance with Article XIV), except
payments and distributions made by the Trustee as permitted by Section 13.9,
until all Senior Debt has been paid in full in cash or other payment
satisfactory to the holders of Senior Debt or such acceleration is rescinded in
accordance with the terms of this Indenture. If payment of the Securities is
accelerated because of an Event of Default, the Company shall promptly notify
holders of Senior Debt of the acceleration.

                                      -85-


<PAGE>


        SECTION 13.4 PAYMENT PERMITTED IF NO DEFAULT.

        Nothing contained in this Article or elsewhere in this Indenture or in
any of the Securities shall prevent (a) the Company, at any time except during
the pendency of any case, proceeding, dissolution, liquidation or other winding
up, assignment for the benefit of creditors or other marshaling of assets and
liabilities of the Company referred to in Section 13.2, or during the
circumstances referred to in the first paragraph of Section 13.2, or under the
conditions described in Section 13.3, from making payments at any time of
principal of (and premium (including any Make-Whole Payment), if any) or
interest on the Securities, or (b) the application by the Trustee of any money
deposited with it hereunder to the payment of or on account of the principal of
(and premium (including any Make-Whole Payment), if any) or interest on the
Securities, if, at the time of such application by the Trustee, it did not have
knowledge that such payment would have been prohibited by the provisions of this
Article.

        SECTION 13.5 SUBROGATION TO RIGHTS OF HOLDERS OF SENIOR DEBT.

        Subject to the payment in full in cash of all Senior Debt, the Holders
of the Securities shall be subrogated to the extent of the payments or
distributions made to the holders of such Senior Debt pursuant to the provisions
of this Article to the rights of the holders of such Senior Debt to receive
payments and distributions of cash, property and securities applicable to the
Senior Debt until the principal of (and premium (including any Make-Whole
Payment), if any) and interest on the Securities shall be paid in full. For
purposes of such subrogation, no payments or distributions to the holders of the
Senior Debt of any cash, property or securities to which the Holders of the
Securities or the Trustee would be entitled except for the provisions of this
Article, and no payments over pursuant to the provisions of this Article to the
holders of Senior Debt by Holders of the Securities or the Trustee, shall, as
among the Company, its creditors other than holders of Senior Debt and the
Holders of the Securities, be deemed to be a payment or distribution by the
Company to or on account of the Senior Debt.

        SECTION 13.6 PROVISIONS SOLELY TO DEFINE RELATIVE RIGHTS.

        The provisions of this Article are and are intended solely for the
purpose of defining the relative rights of the Holders of the Securities on the
one hand and the holders of Senior Debt on the other hand. Nothing contained in
this Article or elsewhere in this Indenture or in the Securities is intended to
or shall (i) impair, as among the Company, its creditors other than holders of
Senior Debt and the Holders of the Securities, the obligation of the Company,
which is absolute and unconditional, to pay to the Holders of the Securities the
principal of (and premium, including any Make-Whole Payment, if any) and
interest on the Securities as and when the same shall become due and payable in
accordance with their terms; or (ii) affect the relative rights against the
Company of the Holders of the Securities and creditors of the Company other than
the holders of Senior Debt; or (iii) prevent the Trustee or the Holder of any
Security from exercising all remedies otherwise permitted by applicable law upon
default under this Indenture, subject to the rights, if any, under this Article
of the holders of Senior Debt to receive cash, property and securities otherwise
payable or deliverable to the Trustee or such Holder.

                                      -86-


<PAGE>


        SECTION 13.7 TRUSTEE TO EFFECTUATE SUBORDINATION.

        Each Holder by its acceptance thereof authorizes and directs the Trustee
on its behalf to take such action as may be necessary or appropriate to
effectuate the subordination provided in this Article and appoints the Trustee
its attorney-in-fact for any and all such purposes. Without limiting the
generality of the foregoing, the Trustee shall, if requested in writing by a
Representative or a holder of Designated Senior Debt, timely file proofs of
claim under Section 5.4 hereof in respect of the Securities prior to any "bar
date" or deadline for the filing thereof.

        SECTION 13.8 NO WAIVER OF SUBORDINATION PROVISIONS.

        No right of any present or future holder of any Senior Debt to enforce
subordination as herein provided shall at any time in any way be prejudiced or
impaired by any act or failure to act on the part of the Company or by any act
or failure to act, in good faith, by any such holder of any Senior Debt, or by
any non- compliance by the Company with the terms, provisions and covenants of
this Indenture, regardless of any knowledge thereof any such holder may have or
be otherwise charged with.

        Without in any way limiting the generality of the foregoing paragraph,
the holders of Senior Debt may, at any time and from time to time, without the
consent of or notice to the Trustee or the Holders of the Securities, without
incurring responsibility to the Holders of the Securities and without impairing
or releasing the subordination provided in this Article or the obligations
hereunder of the Holders of the Securities to the holders of Senior Debt, do any
one or more of the following: (i) change the manner, place or terms of payment
or extend the time of payment of, or renew or alter, Senior Debt, or otherwise
amend or supplement in any manner Senior Debt or any instrument evidencing the
same or any agreement under which Senior Debt is outstanding; (ii) sell,
exchange, release or otherwise deal with any property pledged, mortgaged or
otherwise securing Senior Debt; (iii) release any Person liable in any manner
for the collection of Senior Debt; and (iv) exercise or refrain from exercising
any rights against the Company and any other Person.

        SECTION 13.9 NOTICE TO TRUSTEE.

        The Company shall give prompt written notice to the Trustee of any 
fact known to the Company which would prohibit the making of any payment to 
or by the Trustee in respect of the Securities. Notwithstanding the 
provisions of this Article or any other provision of this Indenture, the 
Trustee shall not be charged with knowledge of the existence of any facts 
which would prohibit the making of any payment to or by the Trustee in 
respect of the Securities, unless and until a Responsible Officer of the 
Trustee shall have received written notice thereof from the Company or a 
Representative or a holder of Senior Debt (including, without limitation, a 
holder of Designated Senior Debt) and, prior to the receipt of any such 
written notice, the Trustee, subject to the provisions of Section 6.1, shall 
be entitled in all respects to assume that no such facts exist; provided, 
however, that if the Trustee shall not have received the notice provided for 
in this Section 13.9 at least three Business Days prior to the date upon 
which by the terms hereof

                                      -87-


<PAGE>


any money may become payable for any purpose (including, without limitation, the
payment of the principal of (and premium (including any Make-Whole Payment), if
any) or interest on any Security), then, anything herein contained to the
contrary notwithstanding, the Trustee shall have full power and authority to
receive such money and to apply the same to the purpose for which such money was
received and shall not be affected by any notice to the contrary which may be
received by it within three Business Days prior to such date.

        Notwithstanding anything in this Article XIII to the contrary, nothing
shall prevent any payment by the Trustee to the Holders of monies deposited with
it pursuant to Section 4.1, and any such payment shall not be subject to the
provisions of Section 13.2 and 13.3.

        Subject to the provisions of Section 6.1, the Trustee shall be entitled
to rely on the delivery to it of a written notice by a Person representing
himself to be a Representative or a holder of Senior Debt (including, without
limitation, a holder of Designated Senior Debt) to establish that such notice
has been given by a Representative or a holder of Senior Debt (including,
without limitation, a holder of Designated Senior Debt). In the event that the
Trustee determines in good faith that further evidence is required with respect
to the right of any Person as a holder of Senior Debt to participate in any
payment or distribution pursuant to this Article, the Trustee may request such
Person to furnish evidence to the reasonable satisfaction of the Trustee as to
the amount of Senior Debt held by such Person, the extent to which such Person
is entitled to participate in such payment or distribution and any other facts
pertinent to the rights of such Person under this Article, and if such evidence
is not furnished, the Trustee may defer any payment to such Person pending
judicial determination as to the right of such Person to receive such payment.

        SECTION 13.10 RELIANCE ON JUDICIAL ORDER OR CERTIFICATE OF LIQUIDATING
AGENT.

        Upon any payment or distribution of assets of the Company referred to in
this Article, the Trustee, subject to the provisions of Section 6.1, and the
Holders of the Securities shall be entitled to rely upon any order or decree
entered by any court of competent jurisdiction in which such insolvency,
bankruptcy, receivership, liquidation, reorganization, dissolution, winding up
or similar case or proceeding is pending, or a certificate of the trustee in
bankruptcy, receiver, liquidating trustee, custodian, assignee for the benefit
of creditors, agent or other Person making such payment or distribution,
delivered to the Trustee or to the Holders, for the purpose of ascertaining the
Persons entitled to participate in such payment or distribution, the holders of
the Senior Debt and other indebtedness of the Company, the amount thereof or
payable thereon, the amount or amounts paid or distributed thereon and all other
facts pertinent thereto or to this Article.

        SECTION 13.11 TRUSTEE NOT FIDUCIARY FOR HOLDERS OF SENIOR DEBT.

        The Trustee shall not be deemed to owe any fiduciary duty to the holders
of Senior Debt and shall not be liable to any such holders if it shall in good
faith mistakenly pay over or

                                      -88-


<PAGE>


distribute to Holders or to the Company or to any other Person cash, property or
securities to which any holders of Senior Debt shall be entitled by virtue of
this Article or otherwise.

         With respect to holders of Senior Debt, the Trustee undertakes to 
perform or to observe only such of its covenants or obligations as are 
specifically set forth in this Article and no implied covenants or 
obligations with respect to holders of Senior Debt shall be read into this 
Indenture against the Trustee.

        SECTION 13.12 RELIANCE BY HOLDERS OF SENIOR DEBT ON SUBORDINATION
PROVISIONS.

        Each Holder by accepting a Security acknowledges and agrees that the
foregoing subordination provisions are, and are intended to be, an inducement
and a consideration to each holder of any Senior Debt, whether such Senior Debt
was created or acquired before or after the issuance of the Securities, to
acquire and continue to hold, or to continue to hold, such Senior Debt and such
holder of Senior Debt shall be deemed conclusively to have relied on such
subordination provisions in acquiring and continuing to hold, or in continuing
to hold, such Senior Debt, and no amendment or modification of the provisions
contained herein shall diminish the rights of such holders of Senior Debt unless
such holders shall have agreed in writing thereto.

        SECTION 13.13 RIGHTS OF TRUSTEE AS HOLDER OF SENIOR DEBT; PRESERVATION
OF TRUSTEE'S RIGHTS.

        The Trustee in its individual capacity shall be entitled to all the
rights set forth in this Article with respect to any Senior Debt which may at
any time be held by it, to the same extent as any other holder of Senior Debt,
and nothing in this Indenture shall deprive the Trustee of any of its rights as
such holder.

        Nothing in this Article shall apply to claims of, or payments to, the
Trustee under or pursuant to Section 6.7.

        SECTION 13.14 ARTICLE APPLICABLE TO PAYING AGENTS.

        In case at any time any Paying Agent other than the Trustee shall have
been appointed by the Company and be then acting hereunder, the term "Trustee"
as used in this Article shall in such case (unless the context otherwise
requires) be construed as extending to and including such Paying Agent within
its meaning as fully for all intents and purposes as if such Paying Agent were
named in this Article in addition to or in place of the Trustee; provided,
however, that Section 13.13 shall not apply to the Company or any Affiliate of
the Company if it or such Affiliate acts as Paying Agent.

                                      -89-


<PAGE>


        SECTION 13.15 CERTAIN [CONVERSIONS AND](69) REPURCHASES DEEMED PAYMENT.

        For the purposes of this Article only, (i) the issuance and delivery of
junior securities [upon conversion of Securities in accordance with Article XII
or](70) upon the repurchase of Securities in accordance with Article XIV shall 
not be deemed to constitute a payment or distribution on account of the 
principal of or premium or interest on Securities or on account of the 
purchase or other acquisition of Securities[, and (ii) the payment, 
issuance or delivery of cash (except in satisfaction of fractional shares 
pursuant to Section 12.3 or 14.3(7)), property or securities (other than 
junior securities) upon conversion of a Security shall be deemed to 
constitute payment on account of the principal of such Security](71). For the 
purposes of this Section, the term "junior securities" means [(a) shares of any
stock of any class of the Company and securities into which the Securities 
are convertible pursuant to Article XII and (b)](72) securities of the 
Company which are subordinated in right of payment to all Senior Debt which 
may be outstanding at the time of issuance or delivery of such securities to 
substantially the same extent as, or to a greater extent than, the Securities 
are so subordinated as provided in this Article. Nothing contained in this 
Article or elsewhere in this Indenture or in the Securities is intended to or 
shall impair, as among the Company, its creditors other than holders of 
Senior Debt and the Holders of the Securities, the right, which is absolute 
and unconditional, of the Holder of any Security [to convert such Security in 
accordance with Article XII or](73) to exchange such Security for Common Stock 
in accordance with Article XIV if the Company elects to satisfy the obligations 
under Article XIV by the delivery of Common Stock.

----------

        (69) INSERT IF SECURITIES ARE CONVERTIBLE

        (70) INSERT IF SECURITIES ARE CONVERTIBLE

        (71) INSERT IF SECURITIES ARE CONVERTIBLE

        (72) INSERT IF SECURITIES ARE CONVERTIBLE

        (73) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -90-


<PAGE>


                                   ARTICLE XIV

                     REPURCHASE OF SECURITIES AT THE OPTION
                     OF THE HOLDER UPON A CHANGE IN CONTROL

        SECTION 14.1 RIGHT TO REQUIRE REPURCHASE.

        In the event that a Change in Control (as hereinafter defined) shall
occur, then each Holder shall have the right, at the Holder's option, but
subject to the provisions of Section 14.2, to require the Company to repurchase,
and upon the exercise of such right the Company shall repurchase, all of such
Holder's Securities not theretofore called for redemption, or any portion of the
principal amount thereof that an integral multiple of U.S. $1,000 (provided that
no single Security may be repurchased in part unless the portion of the
principal amount of such Security to be Outstanding after such repurchase is
equal to an integral multiple of U.S. $1,000), on the date (the "Repurchase
Date") that is 45 days after the date of the Company Notice (as defined in
Section 14.3) at a purchase price equal to _____% of the principal amount of the
Securities to be repurchased plus interest accrued to the Repurchase Date (the
"Repurchase Price"); provided, however, that installments of interest on
Securities whose Stated Maturity is on or prior to the Repurchase Date shall be
payable to the Holders of such Securities, or one or more Predecessor
Securities, registered as such on the relevant Record Date according to their
terms and the provisions of Section 3.7. Such right to require the repurchase of
the Securities shall not continue after a discharge of the Company from its
obligations with respect to the Securities in accordance with Article IV, unless
a Change in Control shall have occurred prior to such discharge. At the option
of the Company, the Repurchase Price may be paid in cash or, subject to the
fulfillment by the Company of the conditions set forth Section 14.2, by delivery
of shares of Common Stock having a fair market value equal to the Repurchase
Price. Whenever in this Indenture (including Sections 2.2, 3.1, 5.1(1) and 5.8)
there is a reference, in any context, to the principal of any Security as of any
time, such reference shall be deemed to include reference to the Repurchase
Price payable in respect of such Security to the extent that such Repurchase
Price is, was or would be so payable at such time, and express mention of the
Repurchase Price in any provision of this Indenture shall not be construed as
excluding the Repurchase Price in those provisions of this Indenture when such
express mention is not made; provided, however, that for the purposes of Article
XIII such reference shall be deemed to include reference to the Repurchase Price
only to the extent the Repurchase Price is payable in cash.

        SECTION 14.2 CONDITIONS TO THE COMPANY'S ELECTION TO PAY THE REPURCHASE
PRICE OR THE MAKE-WHOLE PAYMENT IN COMMON STOCK.

        The Company may elect to pay the Repurchase Price by delivery of shares
of Common Stock pursuant to Section 14.1, and the Company may elect to pay the

                                      -91-


<PAGE>


Make-Whole Payment by delivery of shares of Common Stock pursuant to Section
2.2, if and only if the following conditions shall have been satisfied:

        (1) The shares of Common Stock deliverable in payment of the Repurchase
Price or Make-Whole Payment, as the case may be, shall have a fair market value
as of the Repurchase Date or the Redemption Date, as the case may be, of not
less than the Repurchase Price or Make-Whole Payment, as the case may be. For
purposes of Section 14.1 and this Section 14.2, the fair market value of shares
of Common Stock shall be determined by the Company and shall be equal to ____%
of the average of the Closing Price Per Share for the five consecutive Trading
Days immediately preceding and including the third Trading Day prior to the
Repurchase Date or the Redemption Date, as the case may be;

        (2) The Repurchase Price or Make-Whole Payment, as the case may be,
shall be paid only in cash in the event any shares of Common Stock to be issued
upon repurchase or redemption, as the case may be, of Securities hereunder (i)
require registration under any federal securities law before such shares may be
freely transferable without being subject to any transfer restrictions under the
Securities Act upon repurchase and if such registration is not completed or does
not become effective prior to the Repurchase Date or the Redemption Date, as the
case may be, and/or (ii) require registration with or approval of any
governmental authority under any state law or any other federal law before such
shares may be validly issued or delivered upon repurchase or redemption, as the
case may be, and if such registration is not completed or does not become
effective or such approval is not obtained prior to the Repurchase Date or the
Redemption Date, as the case may be;

        (3) Payment of the Repurchase Price or Make-Whole Payment, as the case
may be, may not be made in Common Stock unless such stock is, or shall have
been, approved for quotation on the Nasdaq National Market or listed on a
national securities exchange, in either case, prior to the Repurchase Date or
the Redemption Date, as the case may be; and

        (4) All shares of Common Stock which may be issued upon repurchase or
redemption, as the case may be, of Securities will be issued out of the
Company's authorized but unissued Common Stock and, will upon issue, be duly and
validly issued and fully paid and non-assessable and free of any preemptive
rights or rights of first refusal.

        If all of the conditions set forth in this Section 14.2 are not
satisfied in accordance with the terms thereof, the Repurchase Price or
Make-Whole Payment, as the case may be, shall be paid by the Company only in
cash.

        SECTION 14.3 NOTICES; METHOD OF EXERCISING REPURCHASE RIGHT, ETC.

        (1) Unless the Company shall have theretofore called for redemption all
of the Outstanding Securities, on or before the 30th day after the occurrence of
a Change in Control, the Company or, at the request and expense of the Company
on or before the 30th day after such occurrence, the Trustee, shall give to all
Holders, in the manner provided in Section 1.6, notice (the "Company Notice") of
the occurrence of the Change of Control and of the repurchase right set forth
herein arising as a result thereof. The Company shall also deliver a copy of
such notice

                                      -92-


<PAGE>


of a repurchase right to the Trustee and notify one or more
nationally-recognized reporting institutions such as Bloomberg of the Change in
Control and repurchase right.

        Each notice of a repurchase right shall state:

                (i) the Repurchase Date,

                (ii) the date by which the repurchase right must be exercised,

                (iii) the Repurchase Price, and whether the Repurchase Price
        shall be paid by the Company in cash or by delivery of shares of Common
        Stock,

                (iv) a description of the procedure which a Holder must follow
        to exercise a repurchase right, and the place or places where such
        Securities are to be surrendered for payment of the Repurchase Price and
        accrued interest, if any to the Repurchase Date,

                (v) that on the Repurchase Date the Repurchase Price, and
        accrued interest, if any to the Repurchase Date, will become due and
        payable upon each such Security designated by the Holder to be
        repurchased, and that interest thereon shall cease to accrue on and
        after said date,

                [(vi) the Conversion Rate then in effect, the date on which the
        right to convert the principal amount of the Securities to be
        repurchased will terminate and the place or places where such Securities
        may be surrendered for CONVERSION,](74) and

                (vii) the place or places that the Notice of Election of Holder
        to Require Repurchase as specified in Section 2.2 shall be delivered.

        No failure of the Company to give the foregoing notices or defect
therein shall limit any Holder's right to exercise a repurchase right or affect
the validity of the proceedings for the repurchase of Securities.

        If any of the foregoing provisions or other provisions of this Article
XIV are inconsistent with applicable law, such law shall govern.

        (2) To exercise a repurchase right, a Holder shall deliver to the
Trustee on or before the 30th day after the date of the Company Notice (i)
irrevocable written notice of the Holder's exercise of such right, which notice
shall set forth the name of the Holder, the principal amount of the Securities
to be repurchased (and, if any Security is to repurchased in part, the serial
number thereof, the portion of the principal amount thereof to be repurchased
and the name of the Person in which the portion thereof to remain Outstanding
after such repurchase is to be

----------

        (74) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -93-


<PAGE>


registered) and a statement that an election to exercise the repurchase right is
being made thereby, and, in the event that the Repurchase Price shall be paid in
shares of Common Stock, the name or names (with addresses) in which the
certificate or certificates for shares of Common Stock shall be issued, and (ii)
the Securities with respect to which the repurchase right is being exercised.
Such written notice shall be irrevocable[, except that the right of the Holder
to convert the Securities with respect to which the repurchase right is being
exercised shall continue until the close of business on the Business Day
immediately preceding the Repurchase Date](75).

        (3) In the event that a repurchase right shall be exercised in
accordance with the terms hereof, the Company shall pay or cause to be paid to
the Trustee the Repurchase Price in cash or shares of Common Stock, as provided
above, for payment to the Holder on the Repurchase Date or, if shares of Common
Stock are to be paid, as promptly after the Repurchase Date as practicable,
together with accrued and unpaid interest to the Repurchase Date payable with
respect to the Securities as to which the repurchase right has been exercised;
provided, however, that installments of interest that mature on or prior to the
Repurchase Date shall be payable in cash to the Holders of such Securities, or
one or more Predecessor Securities, registered as such at the close of business
on the relevant Regular Record Date.

        (4) If any Security (or portion thereof) surrendered for repurchase
shall not be so paid on the Repurchase Date, the principal amount of such
Security (or portion thereof, as the case may be) shall, until paid, bear
interest to the extent permitted by applicable law from the Repurchase Date at
the rate of _____% per annum[, and each Security shall remain convertible into
Common Stock until the principal of such Security (or portion thereof, as the
case may be) shall have been paid or duly provided for](76).

        (5) Any Security which is to be repurchased only in part shall be
surrendered to the Trustee (with, if the Company or the Trustee so requires, due
endorsement by, or a written instrument of transfer in form satisfactory to the
Company and the Trustee duly executed by, the Holder thereof or his attorney
duly authorized in writing), and the Company shall execute, and the Trustee
shall authenticate and make available for delivery to the Holder of such
Security without service charge, a new Security or Securities, containing
identical terms and conditions, each in an authorized denomination in aggregate
principal amount equal to and in exchange for the unrepurchased portion of the
principal of the Security so surrendered.

        (6) Any issuance of shares of Common Stock in respect of the Repurchase
Price shall be deemed to have been effected immediately prior to the close of
business on the Repurchase Date and the Person or Persons in whose name or names
any certificate or certificates for shares of Common Stock shall be issuable
upon such repurchase shall be deemed to have become on the Repurchase Date the
holder or holders of record of the shares represented thereby; provided,
however, that any surrender for repurchase on a date when the stock transfer
books of the

----------

        (75) INSERT IF SECURITIES ARE CONVERTIBLE

        (76) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -94-


<PAGE>


Company shall be closed shall constitute the Person or Persons in whose name or
names the certificate or certificates for such shares are to be issued as the
record holder or holders thereof for all purposes at the opening of business on
the next succeeding day on which such stock transfer books are open. No payment
or adjustment shall be made for dividends or distributions on any Common Stock
issued upon repurchase of any Security declared prior to the Repurchase Date.

        (7) No fractions of shares shall be issued upon repurchase of
Securities. If more than one Security shall be repurchased from the same Holder
and the Repurchase Price shall be payable in shares of Common Stock, the number
of full shares which shall be issuable upon such repurchase shall be computed on
the basis of the aggregate principal amount of the Securities so repurchased.
Instead of any fractional share of Common Stock which would otherwise be
issuable on the repurchase of any Security or Securities, the Company will
deliver to the applicable Holder its check for the current market value of such
fractional share. The current market value of a fraction of a share is
determined by multiplying the current market price of a full share by the
fraction, and rounding the result to the nearest cent. For purposes of this
Section, the current market price of a share of Common Stock is the Closing
Price Per Share on the Trading Day immediately preceding the Repurchase Date.

        (8) Any issuance and delivery of certificates for shares of Common Stock
on repurchase of Securities shall be made without charge to the Holder being
repurchased for such certificates or for any tax or duty in respect of the
issuance or delivery of such certificates or the securities represented thereby;
provided, however, that the Company shall not be required to pay any tax or duty
which may be payable in respect of (i) income of the Holder or (ii) any transfer
involved in the issuance or delivery of certificates for shares of Common Stock
in a name other than that of the Holder of the Securities being repurchased, and
no such issuance or delivery shall be made unless and until the Person
requesting such issuance or delivery has paid to the Company the amount of any
such tax or duty or has established, to the reasonable satisfaction of the
Company, that such tax or duty has been paid.

        (9) All Securities delivered for repurchase shall be delivered to the
Trustee to be canceled at the direction of the Trustee, which shall dispose of
the same as provided in Section 3.9.

        SECTION 14.4 CERTAIN DEFINITIONS.

        For purposes of this Article XIV,

        (1) the term "beneficial owner" shall be determined in accordance with
Rule 13d-3, as in effect on the date of the original execution of this
Indenture, promulgated by the Commission pursuant to the Exchange Act;

                                      -95-


<PAGE>


        (2) a "Change in Control" shall be deemed to have occurred at the time,
after the original issuance of the Securities, of:

                        (i) the acquisition by any Person of beneficial
                ownership, directly or indirectly, through a purchase, merger or
                other acquisition transaction or series of transactions, of
                shares of capital stock of the Company entitling such person to
                exercise 50% or more of the total voting power of all shares of
                capital stock of the Company entitled to vote generally in the
                elections of directors, other than any such acquisition by the
                Company, any subsidiary of the Company or any employee benefit
                plan of the Company; or

                        (ii) any consolidation of the Company with, or merger of
                the Company into, any other Person, any merger of another Person
                into the Company, or any conveyance, sale, transfer or lease of
                all or substantially all of the assets of the Company to another
                Person (other than (a) any such transaction [(x)](77) which does
                not result in any reclassification, conversion, exchange or
                cancellation of outstanding shares of capital stock of the
                Company and (y) pursuant to which the holders of the Common
                Stock immediately prior to such transaction have the entitlement
                to exercise, directly or indirectly, 50% or more of the total
                voting power of all shares of capital stock entitled to vote
                generally in the election of directors of the continuing or
                surviving Person immediately after such transaction and (b) any
                merger which is effected solely to change the jurisdiction of
                incorporation of the Company and results in a reclassification,
                conversion or exchange of outstanding shares of Common Stock
                into solely shares of common stock); provided, however, that a
                Change in Control shall not be deemed to have occurred if (x)
                the Closing Price Per Share on any five Trading Days within the
                period of 10 consecutive Trading Days ending immediately after
                the later of the date of the Change in Control or the date of
                the public announcement of the Change in Control (in the case of
                a Change in Control under clause (i) above) or the period of 10
                consecutive Trading Days ending immediately before the Change in
                Control (in the case of a Change in Control under clause (ii)
                above) shall equal or exceed _______________ [or (y) all of the
                consideration (excluding cash payments for fractional shares and
                cash payments made pursuant to dissenters' appraisal rights) in
                a merger or consolidation otherwise constituting a Change of
                Control under clause (i) and/or clause (ii) above consists of
                shares of common stock traded on a national securities exchange
                or quoted on the Nasdaq National Market (or will be so traded or
                quoted immediately following such merger or consolidation) and
                as a result of such merger or consolidation the notes become
                convertible into such common stock](78).

        [(3) the term "Conversion Price" shall equal U.S. $1,000 divided by the
Conversion Rate (rounded to the nearest cent)](79); -- and

----------

        (77) INSERT IF SECURITIES ARE CONVERTIBLE

        (78) INSERT IF SECURITIES ARE CONVERTIBLE

        (79) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -96-


<PAGE>


        (4) for purposes of Section 14.4(2)(i), the term "Person" shall include
any syndicate or group which would be deemed to be a "Person" under Section
13(d)(3) of the Exchange Act, as in effect on the date of the original execution
of this Indenture.

        [SECTION 14.5 CONSOLIDATION, MERGER, ETC.

        In the case of any merger, consolidation, conveyance, sale, transfer or
lease of all or substantially all of the assets of the Company to which Section
12.11 applies, in which the Common Stock of the Company is changed or exchanged
as a result into the right to receive shares of stock and other securities or
property or assets (including cash) which includes shares of Common Stock of the
Company or common stock of another Person that are, or upon issuance will be,
traded on a United States national securities exchange or approved for trading
on an established automated over-the-counter trading market in the United States
and such shares constitute at the time such change or exchange becomes effective
in excess of 50% of the aggregate fair market value of such shares of stock and
other securities, property and assets (including cash) (as determined by the
Company, which determination shall be conclusive and binding), then the Person
formed by such consolidation or resulting from such merger or combination or
which acquires the properties or assets (including cash) of the Company, as the
case may be, shall execute and deliver to the Trustee a supplemental indenture
(which shall comply with the Trust Indenture Act as in force at the date of
execution of such supplemental indenture) modifying the provisions of this
Indenture relating to the right of Holders to cause the Company to repurchase
the Securities following a Change in Control, including without limitation the
applicable provisions of this Article XIV and the definitions of the Common
Stock and Change in Control, as appropriate, and such other related definitions
set forth herein as determined in good faith by the Company (which determination
shall be conclusive and binding), to make such provisions apply in the event of
a subsequent Change in Control to the common stock and the issuer thereof if
different from the Company and Common Stock of the Company (in lieu of the
Company and the Common Stock of the Company).](80)

                                   ARTICLE XV

         HOLDERS LISTS AND REPORTS BY TRUSTEE AND COMPANY; NON-RECOURSE

     SECTION 15.1 COMPANY TO FURNISH TRUSTEE NAMES AND ADDRESSES OF HOLDERS.

        The Company will furnish or cause to be furnished to the Trustee:

        (1) semi-annually, not more than 15 days after the Regular Record Date,
a list, in such form as the Trustee may reasonably require, of the names and
addresses of the Holders as of such Regular Record Date, and

----------

        (80) INSERT IF SECURITIES ARE CONVERTIBLE

                                      -97-


<PAGE>


        (2) at such other times as the Trustee may reasonably request in
writing, within 30 days after the receipt by the Company of any such request, a
list of similar form and content as of a date not more than 15 days prior to the
time such list is furnished; excluding from any such list names and addresses
received by the Trustee acting in its capacity as Security Registrar.

        SECTION 15.2 PRESERVATION OF INFORMATION.

        (1) The Trustee shall preserve, in as current a form as is reasonably
practicable, the names and addresses of Holders contained in the most recent
list furnished to the Trustee as provided in Section 15.1 and the names and
addresses of Holders received by the Trustee in its capacity as Security
Registrar. The Trustee may destroy any list, if any, furnished to it as provided
in Section 15.1 upon receipt of a new list so furnished.

        (2) The rights of Holders to communicate with other Holders with respect
to their rights under this Indenture or under the Securities, and the
corresponding rights and duties of the Trustee, shall be as provided by the
Trust Indenture Act.

        (3) Every Holder, by receiving and holding the same, agrees with the
Company and the Trustee that neither the Company nor the Trustee nor any agent
of either of them shall be held accountable by reason of any disclosure of
information as to names and addresses of Holders made pursuant to the Trust
Indenture Act.

        SECTION 15.3 REPORTS BY TRUSTEE.

        (1) The Trustee shall transmit to Holders such reports concerning the
Trustee and its actions under this Indenture as may be required pursuant to the
Trust Indenture Act at the times and in the manner provided pursuant thereto.

        (2) A copy of each such report shall, at the time of such transmission
to Holders, be filed by the Trustee with each stock exchange upon which the
Securities are listed, with the Commission and with the Company. The Company
will notify the Trustee when the Securities are listed on any stock exchange.

        SECTION 15.4 REPORTS BY COMPANY.

        The Company shall file with the Trustee and the Commission, and transmit
to Holders, such information, documents and other reports, and such summaries
thereof, as may be required pursuant to the Trust Indenture Act at the times and
in the manner provided pursuant to the Trust Indenture Act; provided that any
such information, documents or reports required to be filed with

                                      -98-


<PAGE>


the Commission pursuant to Section 13 or 15(d) of the Exchange Act shall be
filed with the Trustee within 15 days after the same is so required to be filed
with the Commission.

         Delivery of such reports, information and documents to the Trustee 
is for informational purposes only and the Trustee's receipt of such shall 
not constitute constructive notice of any information contained therein or 
determinable from information contained therein, including the Company's 
compliance with any of its covenants hereunder (as to which the Trustee is 
entitled to conclusively rely exclusively on Officers' Certificates).

                                   ARTICLE XVI

         IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS AND DIRECTORS

        SECTION 16.1 INDENTURE AND SECURITIES SOLELY CORPORATE OBLIGATIONS.

        No recourse for the payment of the principal of or premium (including
any Make-Whole Payment), if any, or interest on any Security and no recourse
under or upon any obligation, covenant or agreement of the Company in this
Indenture or in any supplemental indenture or in any Security, or because of the
creation of any indebtedness represented thereby, shall be had against any
incorporator, stockholder, employee, agent, officer, or director or subsidiary,
as such, past, present or future, of the Company or of any successor
corporation, whether by virtue of any constitution, statute or rule of law, or
by the enforcement of any assessment or penalty or otherwise; it being expressly
understood that all such liability is hereby waived and released as a condition
of, and as a consideration for, the execution of this Indenture and the issue of
the Securities.

        This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.

        IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed all as of the day and year first above written.


SONUS NETWORKS, INC.

By:
   ____________________________
Name:
Title:

_______________________________,
as Trustee

By:
   ____________________________
Name:
Title:



                                      -99-




<PAGE>

                                                                   EXHIBIT 5.1


                                     June 21, 2001


Sonus Networks, Inc.
5 Carlisle Avenue
Westford, MA 01886


Ladies and Gentlemen:

         We are acting as counsel to Sonus Networks, Inc., a Delaware 
corporation (the "COMPANY"), in connection with the Company's registration 
statement on Form S-3, File No. 333-61940 (as amended by Amendment No. 1 
referred to below, the "REGISTRATION STATEMENT"), originally filed on May 31, 
2001 with the Securities and Exchange Commission (the "COMMISSION") under the 
Securities Act of 1933, as amended (the "SECURITIES ACT"), as amended by 
pre-effective Amendment No. 1 thereto filed with the Commission on the date 
hereof ("AMENDMENT NO. 1"), relating to the proposed public offering of up to 
$1,000,000,000 aggregate initial offering price of the following securities 
of the Company: (i) senior debt securities (the "SENIOR DEBT SECURITIES"), 
(ii) subordinated debt securities (the "SUBORDINATED DEBT SECURITIES" and 
collectively with the Senior Debt Securities, the "DEBT SECURITIES"), (iii) 
shares of common stock, $0.001 par value per share (the "COMMON STOCK"), 
including shares of Common Stock that may be issuable upon conversion, 
redemption or repurchase of any Debt Securities or exercise of any Warrants 
(as defined below), (iv) warrants to purchase Debt
 Securities (the "DEBT 
WARRANTS"), and (v) warrants to purchase shares of Common Stock (the "COMMON 
STOCK WARRANTS" and collectively with the Debt Warrants, the "WARRANTS"). The 
Debt Securities, the Common Stock and the Warrants are herein referred to as 
the "REGISTERED SECURITIES". The Registered Securities may be offered and 
sold by the Company from time to time pursuant to Rule 415 under the 
Securities Act as set forth in the "base" prospectus which forms a part of 
the Registration Statement (the "PROSPECTUS"), and as to be set forth in one 
or more supplements to the Prospectus that may be filed under the Securities 
Act. This opinion letter is furnished to you at your request to enable you to 
fulfill the requirements of Item 601(b)(5) of Regulation S-K, 17 C.F.R. 
Section 229.601(b)(5), in connection with the filing of the Registration 
Statement.


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June 21, 2001
Page 2

         As such counsel, we have reviewed the corporate proceedings taken by
the Company with respect to the registration of the Registered Securities. We
have also examined and relied upon originals or copies, certified or otherwise
authenticated to our satisfaction, of such corporate records, documents,
agreements or other instruments of the Company, and such certificates and
records of public officials, and such other papers, as we have deemed necessary
or appropriate in connection herewith. As to all matters of fact (including
factual conclusions and characterizations and descriptions of purpose, intention
or other state of mind) we have relied entirely upon certificates of officers of
the Company, and have assumed, without independent inquiry, the accuracy of
those certificates. We have assumed the genuineness of all signatures, the
conformity to the originals of all documents reviewed by us as copies, the
authenticity and completeness of all original documents reviewed by us in
original or copy form and the legal competence of each individual executing any
applicable document.

         For purposes of this opinion letter, we have assumed that:

         (i)   the issuance, sale, amount, and terms of the Registered
               Securities to be offered from time to time will be duly
               authorized and established by proper action of the Board of
               Directors of the Company, and in accordance with the 
               Fourth Amended and Restated Certificate of Incorporation 
               of the Company, as amended from time to time, the Amended 
               and Restated By-laws of the Company as amended from time 
               to time, and applicable Delaware law, and that, at the time 
               of each such issuance and sale of such Registered Securities, 
               the Company will continue to be validly existing and in good 
               standing under the laws of the State of Delaware, with the 
               requisite corporate power and authority to issue and sell all
               such Registered Securities at such time;

         (ii)  any Senior Debt Securities will be issued pursuant to an
               indenture (each, a "SENIOR INDENTURE"), entered into by the
               Company and a duly qualified trustee (each, a "TRUSTEE"),
               substantially in the form of the form of indenture filed as
               Exhibit 4.2 to Amendment No. 1, and such Senior Debt Securities
               will be in the form of such Senior Debt Security contained in
               such Senior Indenture, and that, at the time any Senior Debt
               Securities are so issued, the related Senior Indenture will have
               been executed and delivered by, and will constitute a valid,
               binding, enforceable agreement of the Company and the applicable
               Trustee party thereto;

         (iii) any Subordinated Debt Securities will be issued pursuant to an
               indenture (each, a "SUBORDINATED INDENTURE"), entered into by the
               Company and a Trustee, substantially in the form of indenture
               filed as Exhibit 4.3 to Amendment No. 1, and will be in the form
               of such Subordinated Debt Security contained in such Subordinated
               Indenture, and that, at the time 



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June 21, 2001
Page 3

               any Subordinated Debt Securities are so issued, the related
               Subordinated Indenture will have been executed and delivered by,
               and will constitute a valid, binding, enforceable agreement of
               the Company and the applicable Trustee party thereto;

         (iv)  any Warrants will be issued under one or more valid, binding, and
               enforceable warrant agreements (each a "WARRANT AGREEMENT"), each
               to be between the Company and a financial institution identified
               therein as a warrant agent (each a "WARRANT AGENT"); and

         (v)   any shares of Common Stock issued pursuant to the Registration 
               Statement from time to time will not exceed the maximum 
               authorized number of shares of Common Stock under the Fourth 
               Amended and Restated Certificate of Incorporation of the 
               Company, as the same may have been amended, minus that number 
               of shares of Common Stock that may have been issued and are 
               outstanding, or are reserved for issuance for other purposes, 
               at such time.

         Each opinion set forth below is subject to the following general
qualifications:

               (a) The enforceability of any obligation of the Company under the
         Debt Securities or otherwise may be limited by bankruptcy, insolvency,
         reorganization, moratorium, marshaling or other laws and rules of law
         affecting the enforcement generally of creditors' rights and remedies
         (including such as may deny giving effect to waivers of debtors' or
         guarantors' rights); and we express no opinion as to the status under
         any fraudulent conveyance laws or fraudulent transfer laws of any of
         the obligations of the Company under the Debt Securities or otherwise.

               (b) No opinion is given herein as to the availability of any
         specific or equitable relief of any kind or as to the enforceability of
         any particular contractual provision relating to remedies after
         default.

               (c) The enforcement of any rights of the holders of the Debt
         Securities and any Trustee may in all cases be subject to an implied
         duty of good faith and fair dealing and to general principles of equity
         (whether such enforcement is considered in a proceeding at law or in
         equity).

               (d) We express no opinion as to the enforceability of any
         particular provision of any of the Debt Securities constituting or
         relating to (i) waivers of rights to object to jurisdiction or venue,
         or consents to jurisdiction or venue, (ii) waivers of rights to (or
         methods of) service of process, or rights to trial by jury, or other
         rights or benefits bestowed by operation of law, (iii) waivers of any
         applicable defenses, setoffs, recoupments, or counterclaims, (iv)
         waivers or 



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June 21, 2001
Page 4

         variations of provisions which are not capable of waiver or variation
         under Sections 1-102(3), 9-501(3), or other provisions of the Uniform
         Commercial Code of any applicable jurisdiction, (v) the grant of powers
         of attorney or proxies to any holders of the Debt Securities or any
         Trustee, (vi) exculpation or exoneration clauses, indemnity clauses,
         and clauses relating to releases or waivers of unmatured claims or
         rights, (vii) submission to binding arbitration, or (viii) the
         imposition or collection of interest on overdue interest or providing
         for a penalty rate of interest or late charges on overdue or defaulted
         obligations, or the payment of any premium, liquidated damages, or
         other amount which may be held by any court to be a "penalty" or a
         "forfeiture". 

               (e) No opinion is given herein as to the effect of usury laws
         or other laws regulating the maximum rate of interest which may be
         charged, taken or received of any jurisdiction. We express no opinion
         as to the enforceability or effectiveness of any so-called "usury
         savings clauses" or other provisions of the Debt Securities purporting
         to specify methods of, or otherwise assure, compliance with usury laws.

               (f) We note that, under the laws of the Commonwealth of
         Massachusetts, the remedies available in the Commonwealth of
         Massachusetts for the enforcement of the Debt Securities could be
         affected by any failure of any holders of Debt Securities or any
         Trustee to file, pursuant to Massachusetts General Laws Chapter 181,
         Section 4, where applicable, the certificates and reports with the
         Secretary of State of the Commonwealth of Massachusetts required of
         every foreign corporation doing business in the Commonwealth; and we
         also note that, under Article 13 of the New York Business Corporation
         Law, the remedies available in the State of New York for the
         enforcement of any Debt Securities could be affected by any failure of
         any holder of Debt Securities or any Trustee, if not organized in the
         State of New York but doing business in the State of New York, to
         become authorized to do so. Further, no opinion is given herein as to
         any other similar laws or requirements in any other jurisdiction.

               (g) No opinion is given herein as to the enforceability of any
         particular provision of any agreement or instrument, relating to
         indemnification under any securities or other laws or contribution in
         lieu of such indemnification.

         Subject to the limitations set forth below, we have made such
examination of law as we have deemed necessary for the purposes of expressing
the opinions set forth in this letter. Such opinions are limited solely to (i)
the internal, substantive laws of the Commonwealth of Massachusetts as applied
by courts located in Massachusetts without regard to choice of law, (ii) the
General Corporation Law of the State of Delaware as applied by courts located in
Delaware, the applicable provisions of the Delaware Constitution and the 
reported judicial decisions interpreting those laws, and (iii) solely with 
respect to the Warrants and the Debt Securities, the internal, substantive 
laws of the State of New York as 



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June 21, 2001
Page 5

applied by courts located in New York, in each case to the extent that the same
may apply to or govern such transactions. We note that any Debt Securities will
contain a provision stating that they shall be governed by, and construed in
accordance with, the laws of the State of New York (the "CHOSEN-LAW PROVISION").
No opinion is given herein as to the Chosen-Law Provision, or otherwise as to
the choice of law or internal substantive rules of law that any court or other
tribunal may apply to the Debt Securities.

         To the extent that the obligations of the Company under any Senior
Indenture or Subordinated Indenture may be dependent upon such matters, we
assume for purposes of this opinion that the Trustee thereunder is duly
organized, validly existing and in good standing under the laws of its
jurisdiction of organization; that the Trustee is duly qualified to engage in
the activities contemplated by such Indenture; that such Indenture has been duly
authorized, executed and delivered by the Trustee and constitutes the valid and
binding obligation of the Trustee enforceable against the Trustee in accordance
with its terms; that the Trustee is in compliance, with respect to acting as a
trustee under such Indenture, with all applicable laws and regulations; and that
the Trustee has the requisite organizational and legal power and authority to
perform its obligations under such Indenture.

         To the extent that the obligations of the Company under any Warrant 
Agreement may be dependent upon such matters, we assume for purposes of this 
opinion that the applicable Warrant Agent is duly organized, validly 
existing, and in good standing under the laws of its jurisdiction of 
organization; that the Warrant Agent is duly qualified to engage in the 
activities contemplated by the Warrant Agreement; that the Warrant Agreement 
has been duly authorized, delivered by the Warrant Agent and constitutes the 
valid and binding obligation of the Warrant Agent enforceable against the 
Warrant Agent in accordance with its terms; that the Warrant Agent is in 
compliance, with respect to acting as a Warrant Agent under the Warrant 
Agreement, with all applicable laws and regulations; and that the Warrant 
Agent has the requisite organizational and legal power and authority to 
perform its obligations under the Warrant Agreement.

         Based upon the foregoing, we are of the opinion that:

         1. Following effectiveness of the Registration Statement and due
execution and delivery of a Senior Indenture by the Company and the Trustee
named therein, the Senior Debt Securities registered under the Registration
Statement, when duly authorized, executed, authenticated and delivered against
the full payment specified therefor in accordance with the terms of the Senior
Indenture and the applicable underwriting agreement pertaining thereto as
described in the Registration Statement, or (in the case of Senior Debt
Securities acquired upon the exercise of Debt Warrants) when upon such exercise
the Company (rather than the payment specified in an underwriting agreement)



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June 21, 2001
Page 6

shall have received the full payment of any specified additional consideration
which is payable for such Senior Debt Securities pursuant to such Debt Warrants
upon such exercise, will constitute binding obligations of the Company in
accordance with their terms.

         2. Following effectiveness of the Registration Statement and due
execution and delivery of a Subordinated Indenture by the Company and the
Trustee named therein, the Subordinated Debt Securities registered under the
Registration Statement, when duly authorized, executed, authenticated and
delivered against the full payment specified therefor in accordance with the
terms of the Subordinated Indenture and the applicable underwriting agreement
pertaining thereto as described in the Registration Statement, or (in the case
of Subordinated Debt Securities acquired upon the exercise of Debt Warrants)
when upon such exercise the Company (rather than the payment specified in an
underwriting agreement) shall have received the full payment of any additional
specified consideration which is payable for such Subordinated Debt Securities
pursuant to such Debt Warrants upon such exercise, will constitute binding
obligations of the Company in accordance with their terms.

         3. Following effectiveness of the Registration Statement, the shares of
Common Stock registered under the Registration Statement, when duly authorized
and issued against the full payment specified therefore in accordance with the
terms of the applicable underwriting agreement pertaining thereto as described
in the Registration Statement, which shall not have a value not less than the
par value thereof, or (in the case of Common Stock issued upon the exercise of
Warrants) when, upon the exercise of the applicable Warrants, the Company
(rather than the payment specified in an underwriting agreement) shall have
received the full amount of any additional specified consideration which is
payable for such Common Stock pursuant to such Warrants upon such exercise
(which must have a value not less than the par value of the relevant Common
Stock), will be validly issued, fully paid and nonassessable.

         4. Following effectiveness of the Registration Statement, the Warrants
registered under the Registration Statement, when duly authorized, executed and
delivered against the payment specified therefor in accordance with the terms of
the applicable underwriting agreement pertaining thereto as described in the
Registration Statement, and pursuant to a Warrant Agreement or agreements duly
authorized, executed and delivered by the Company and a Warrant Agent, will be
validly issued, fully paid and non-assessable.

         This opinion letter is given as of the date hereof, and we express no
opinion as to the effect of subsequent events or changes in law occurring or
becoming effective after the date hereof. We assume no obligation to update this
opinion letter or otherwise advise you with respect to any facts or
circumstances or changes in law that may hereafter occur or come to our
attention.



<PAGE>

June 21, 2001
Page 7

         We hereby consent to the filing of this opinion as an exhibit to the 
Registration Statement and to the reference to this firm under the heading 
"Legal Matters" in the Prospectus included in the Registration Statement. In 
rendering this opinion and giving this consent, we do not admit that we are 
an "expert" within the meaning of the Securities Act.

                                                    Very truly yours,


                                                    /s/ Bingham Dana LLP
                                                    BINGHAM DANA LLP





<PAGE>
                                                                    EXHIBIT 23.1
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
As independent public accountants, we hereby consent to the incorporation by
reference in this registration statement on Form S-3, of our report dated
January 15, 2001 (except with respect to the matters discussed in Note 2 as to
which the date is January 18, 2001) included in Sonus Networks, Inc.'s
Form 10-K for the year ended December 31, 2000 and to all references to our Firm
included in this registration statement.
 
                                                         /s/ Arthur Andersen LLP
Boston, Massachusetts
June 20, 2001





<PAGE>
                                                                    EXHIBIT 23.2
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
As independent public accountants, we hereby consent to the incorporation by
reference in this registration statement on Form S-3, of our report dated
March 5, 2001 (except with respect to the matter discussed in Note 2 as to which
the date is June 6, 2001) included in Sonus Networks, Inc.'s Form 8-K filed on
June 21, 2001 and to all references to our Firm included in this registration
statement.
 
                                                         /s/ Arthur Andersen LLP
Boston, Massachusetts
June 21, 2001





<PAGE>


                                                                   Exhibit 25.1


===============================================================================
                                    FORM T-1

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                            STATEMENT OF ELIGIBILITY
                   UNDER THE TRUST INDENTURE ACT OF 1939 OF A
                    CORPORATION DESIGNATED TO ACT AS TRUSTEE

                      CHECK IF AN APPLICATION TO DETERMINE
                      ELIGIBILITY OF A TRUSTEE PURSUANT TO
                             SECTION 305(b)(2) |__|

                      

                              THE BANK OF NEW YORK
               (Exact name of trustee as specified in its charter)

New York                                                13-5160382
(State of incorporation                                 (I.R.S. employer
if not a U.S. national bank)                            identification no.)

One Wall Street, New York, N.Y.                         10286
(Address of principal executive offices)                (Zip code)

                      
                                  -------------
                              Sonus Networks, Inc.
               (Exact name of obligor as specified in its charter)


Delaware                                                 04-3387074
(State or other jurisdiction of                          (I.R.S. employer
incorporation or organization)                           identification no.)


5 Carlisle Road
Westford, Massachusetts                                  01886
(Address of principal executive offices)                 (Zip code)

                                  -------------

                                 Debt Securities
                       (Title of the indenture securities)

================================================================================


<PAGE>


1.  GENERAL INFORMATION.  FURNISH THE FOLLOWING INFORMATION AS TO THE TRUSTEE:

    (a)  NAME AND ADDRESS OF EACH EXAMINING OR SUPERVISING AUTHORITY TO WHICH 
         IT IS SUBJECT.

--------------------------------------------------------------------------------
                  Name                             Address
--------------------------------------------------------------------------------

Superintendent of Banks of the State of      2 Rector Street, New York,
New York                                     N.Y.  10006, and Albany, N.Y. 12203

Federal Reserve Bank of New York             33 Liberty Plaza, New York,
                                             N.Y.  10045


Federal Deposit Insurance Corporation        Washington, D.C.  20429

New York Clearing House Association          New York, New York   10005

    (b)  WHETHER IT IS AUTHORIZED TO EXERCISE CORPORATE TRUST POWERS.

         Yes.

2.  AFFILIATIONS WITH OBLIGOR.

    IF THE OBLIGOR IS AN AFFILIATE OF THE TRUSTEE, DESCRIBE EACH SUCH 
    AFFILIATION.

    None.

16. LIST OF EXHIBITS.

    EXHIBITS IDENTIFIED IN PARENTHESES BELOW, ON FILE WITH THE COMMISSION, ARE
    INCORPORATED HEREIN BY REFERENCE AS AN EXHIBIT HERETO, PURSUANT TO RULE
    7a-29 UNDER THE TRUST INDENTURE ACT OF 1939 (THE "ACT") AND 17 C.F.R.
    229.10(d).

    1.  A copy of the Organization Certificate of The Bank of New York (formerly
        Irving Trust Company) as now in effect, which contains the authority to
        commence business and a grant of powers to exercise corporate trust
        powers. (Exhibit 1 to Amendment No. 1 to Form T-1 filed with
        Registration Statement No. 33-6215, Exhibits 1a and 1b to Form T-1 filed
        with Registration Statement No. 33-21672 and Exhibit 1 to Form T-1 filed
        with Registration Statement No. 33-29637.)

    4.  A copy of the existing By-laws of the Trustee. (Exhibit 4 to Form T-1
        filed with Registration Statement No. 33-31019.)

    6.  The consent of the Trustee required by Section 321(b) of the Act.
        (Exhibit 6 to Form T-1 filed with Registration Statement No. 33-44051.)

    7.  A copy of the latest report of condition of the Trustee published
        pursuant to law or to the requirements of its supervising or examining
        authority.


                                      -2-

<PAGE>


                                    SIGNATURE


        Pursuant to the requirements of the Act, the Trustee, The Bank of New
York, a corporation organized and existing under the laws of the State of New
York, has duly caused this statement of eligibility to be signed on its behalf
by the undersigned, thereunto duly authorized, all in The City of New York, and
State of New York, on the 30th day of May, 2001.


                                       THE BANK OF NEW YORK



                                       By:  /s/  MARY LAGUMINA          
                                          ----------------------------------
                                          Name:  MARY LAGUMINA
                                          Title:  VICE PRESIDENT