<PAGE>
                            SCHEDULE 14A INFORMATION
 
                  Proxy Statement Pursuant to Section 14(a) of
            the Securities Exchange Act of 1934 (Amendment No.    )
 

<TABLE>
      <S>        <C>
      Filed by the Registrant /X/
 
      Filed by a Party other than the Registrant / /
 
      Check the appropriate box:
      /X/        Preliminary Proxy Statement
      / /        CONFIDENTIAL, FOR USE OF THE COMMISSION ONLY (AS PERMITTED
                 BY RULE 14A-6(E)(2))
      / /        Definitive Proxy Statement
      / /        Definitive Additional Materials
      / /        Soliciting Material Pursuant to Section240.14a-12
 
                                               SONUS NETWORKS,
                                       INC.
      -----------------------------------------------------------------------
                 (Name of Registrant as Specified In Its Charter)
 
      -----------------------------------------------------------------------
           (Name of Person(s) Filing Proxy Statement, if other than the
                                    Registrant)
</TABLE>

 
Payment of Filing Fee (Check the appropriate box):
 

<TABLE>
<S>        <C>  <C>
/X/        No fee required.
/ /        Fee computed on table below per Exchange Act Rules 14a-6(i)(4)
           and 0-11.
           (1)  Title of each class of securities to which transaction
                applies:
                ------------------------------------------------------------
           (2)  Aggregate number of securities to which transaction applies:
                ------------------------------------------------------------
           (3)  Per unit price or other underlying value of transaction
                computed pursuant to Exchange Act Rule 0-11 (set forth the
                amount on which the filing fee is calculated and state how
                it was determined):
                ------------------------------------------------------------
           (4)  Proposed maximum aggregate value of transaction:
                ------------------------------------------------------------
           (5)  Total fee paid:
                ------------------------------------------------------------
 
/ /        Fee paid previously with preliminary materials.
 
           Check box if any part of the fee is offset as provided by
/ /        Exchange Act Rule 0-11(a)(2) and identify the filing for which
           the offsetting fee was paid previously. Identify the previous
           filing by registration statement number, or the Form or Schedule
           and the date of its filing.
 
           (1)  Amount Previously Paid:
                ------------------------------------------------------------
           (2)  Form, Schedule or Registration Statement No.:
                ------------------------------------------------------------
           (3)  Filing Party:
                ------------------------------------------------------------
           (4)  Date Filed:
                ------------------------------------------------------------
</TABLE>


<PAGE>
[LOGO]
 
Sonus Networks, Inc.
5 Carlisle Road
Westford, MA 01886
 
April 16, 2001
 
Dear Shareholder:
 
    We cordially invite you to attend Sonus' annual shareholders' meeting. The
meeting will be held on Friday, May 11, 2001, at 9 a.m. at The Westford Regency,
219 Littleton Road in Westford, Massachusetts.
 
    In the short time since our founding, Sonus has established itself as a
premier telecommunications equipment supplier with whom customers want to do
business and employees want to build their futures. These are the keys to
building long-term shareholder value.
 
    The Notice of Annual Meeting and Proxy Statement accompanying this letter
describes the business to be acted upon at the meeting. Our Annual Report for
2000 is also enclosed. To ensure that your shares are represented at the
meeting, you are urged to vote by proxy as described in the accompanying notice.
 
Thank you for your support of Sonus.
 
Sincerely,
 

<TABLE>
<S>                                                         <C>
Rubin Gruber                                                Hassan M. Ahmed
                                                            President and Chief Executive
Chairman of the Board of Directors                            Officer
</TABLE>

 
--------------------------------------------------------------------------------
The notice of meeting and proxy statement and accompanying proxy card are being
distributed on or about April 16, 2001.

<PAGE>
[LOGO]
 
                              SONUS NETWORKS, INC.
                                5 CARLISLE ROAD
                               WESTFORD, MA 01886
                            ------------------------
 
                    NOTICE OF ANNUAL MEETING OF SHAREHOLDERS
                            TO BE HELD MAY 11, 2001
 
To the Shareholders of Sonus Networks, Inc.:
 
    The 2001 Annual Meeting of Shareholders of Sonus Networks, Inc., will be
held on Friday, May 11, at 9:00 A.M., local time, at The Westford Regency, 219
Littleton Road, Westford, Massachusetts 01886. At the meeting we will:
 
    1.  Elect two (2) directors to serve for three-year terms;
 
    2.  Vote on an amendment to Sonus' Amended and Restated Certificate of
       Incorporation to increase the number of authorized shares of Common Stock
       from 300,000,000 shares to 600,000,000 shares;
 
    3.  Ratify the appointment of Arthur Andersen LLP as independent auditors
       for fiscal 2001; and
 
    4.  Transact any other business that may properly come before the meeting or
       any adjournments thereof.
 
    Shareholders who owned shares of Sonus Common Stock of record at the close
of business on April 11, 2001 are entitled to attend and vote at the meeting. If
you cannot attend, you may vote by telephone or by using the Internet as
instructed on the enclosed Proxy Card or by mailing the Proxy Card in the
enclosed postage-paid envelope. Any shareholder attending the meeting may vote
in person, even if you have already voted on the proposals described in this
proxy statement. A complete list of Sonus' shareholders will be available at the
corporate offices at 5 Carlisle Road, Westford, Massachusetts 01886 prior to the
meeting.
 
                                          By Order of the Board of Directors,
 
                                          Michael G. Hluchyj
                                          Secretary
 
Westford, Massachusetts
April 16, 2001
 
--------------------------------------------------------------------------------
WHETHER OR NOT YOU PLAN TO ATTEND THE ANNUAL MEETING, PLEASE COMPLETE, DATE AND
SIGN THE ENCLOSED PROXY CARD AND MAIL IT PROMPTLY IN THE ENCLOSED STAMPED
ENVELOPE OR VOTE ELECTRONICALLY VIA THE INTERNET OR VOTE BY TELEPHONE IN ORDER
TO ASSURE REPRESENTATION OF YOUR SHARES AT THE ANNUAL MEETING. NO POSTAGE NEED
BE AFFIXED IF MAILED IN THE UNITED STATES.

<PAGE>
                              SONUS NETWORKS, INC.
                                PROXY STATEMENT
 
                   INFORMATION CONCERNING SOLICITATION AND VOTING
 
    Our Board of Directors is soliciting proxies for the 2001 Annual Meeting of
Shareholders. This Proxy Statement contains important information for you to
consider when deciding how to vote on the matters brought before the meeting.
Please read it carefully. PLEASE NOTE THAT THE SHARE AND PER SHARE DATA IN THIS
PROXY STATEMENT HAS BEEN ADJUSTED TO TAKE INTO ACCOUNT OUR THREE-FOR-ONE STOCK
SPLIT (EFFECTED AS A DIVIDEND) IN OCTOBER 2000.
 
    Voting materials, which include this Proxy Statement, Proxy Card and 2000
Annual Report to Shareholders, were mailed to shareholders on or about
April 16, 2001. Our principal executive offices are located at 5 Carlisle Road,
Westford, Massachusetts 01886. Our telephone number is (978) 692-8999.
 
                             QUESTIONS AND ANSWERS
 
Q: Who may vote at the meeting?
 
A: The Board set April 11, 2001 as the record date for the meeting. All
    shareholders who owned Sonus Common Stock of record at the close of business
    on April 11, 2001 may attend and vote at the meeting. Each shareholder is
    entitled to one vote for each share of Common Stock held on all matters to
    be voted on. On April 11, 2001 approximately [xxx,xxx,xxx] shares of Sonus
    Common Stock were outstanding.
 
Q. How many votes does Sonus need to be present at the meeting?
 
A: A majority of Sonus' outstanding shares of Common Stock as of the record date
    must be present at the meeting in order to hold the meeting and conduct
    business. This is called a quorum. Shares are counted as present at the
    meeting if you:
 
    - are present and vote in person at the meeting; or
 
    - have properly submitted a Proxy Card or voted by telephone or using the
      Internet.
 
Q: What proposals will be voted on at the meeting?
 
A: There are three proposals scheduled to be voted on at the meeting:
 
    - Election of two (2) directors to serve for three-year terms;
 
    - Amendment to our Certificate of Incorporation to increase the number of
      authorized shares of Common Stock; and
 
    - Ratification of Arthur Andersen LLP as Sonus' independent auditors.
 
Q: What is the voting requirement to approve each of the proposals?
 
A: In Proposal One for the election of the directors, those two nominees who
    receive the highest number of affirmative "FOR" votes of the shares present
    or represented and entitled to vote at the annual meeting, will be elected.
    To be passed, Proposal Two requires the affirmative "FOR" vote of a majority
    of the shares of Sonus Common Stock outstanding and entitled to vote on
    April 11, 2001. To be passed, Proposal Three requires the affirmative "FOR"
    vote of a majority of the shares voting at the meeting and entitled to vote.
 
Q: How are the votes counted?
 
A: In the election of directors, you may vote "FOR" all of the nominees or your
    vote may be "WITHHELD" with respect to one or more of the nominees. You may
    vote "FOR," "AGAINST" or "ABSTAIN" on the other proposals. If you abstain
    from voting on the other proposals, it has
 
                                       2

<PAGE>
    the same effect as a vote against Proposal Two, but it has no effect on
    Proposal Three. If you just sign your Proxy Card with no further
    instructions, your shares will be counted as a vote "FOR" each director and
    "FOR" the amendment to the Certificate of Incorporation and the ratification
    of Arthur Andersen LLP as Sonus' independent auditors. If you do not vote
    and you hold your shares in a brokerage account in your broker's name (this
    is called "street name"), your broker will have discretionary authority to
    vote your shares "FOR" each director or to withhold votes for each or every
    director. Because your broker will not have discretionary authority to vote
    on Proposal Two if you do not instruct your broker how to vote, your failure
    to direct the vote will have the effect of a vote "AGAINST" Proposal Two.
    These shares, however, will be counted for the purpose of establishing a
    quorum for the meeting. Your broker will also have the discretionary
    authority to vote your shares "FOR" or "AGAINST" Proposal Three. Voting
    results are tabulated and certified by our transfer agent, American Stock
    Transfer & Trust Company.
 
Q: How may I vote my shares in person at the meeting?
 
A: Shares held directly in your name as the shareholder of record may be voted
    in person at the meeting. If you choose to attend the meeting, please bring
    the enclosed Proxy Card or proof of identification for entrance to the
    meeting. If you hold your shares in street name, you must request a legal
    proxy from your stockbroker in order to vote at the meeting.
 
Q: How can I vote my shares without attending the meeting?
 
A: Whether you hold shares directly as a shareholder of record or beneficially
    in street name, you may vote without attending the meeting. You may vote by
    granting a proxy, or for shares held in street name, by submitting voting
    instructions to your stockbroker or nominee. In most cases, you will be able
    to do this by telephone, using the Internet or by mail. Please refer to the
    summary instructions included on your Proxy Card. For shares held in street
    name, the voting instruction card will be included by your stockbroker or
    nominee.
 
BY TELEPHONE OR THE INTERNET--If you have telephone or Internet access, you may
    submit your proxy from anywhere in the world by following the instructions
    on the Proxy Card.
 
BY MAIL--You may submit your proxy by mail by signing your Proxy Card or, for
    shares held in street name, by following the voting instruction card
    included by your stockbroker or nominee and mailing it in the enclosed,
    postage-paid envelope. If you provide specific voting instructions, your
    shares will be voted as you have instructed.
 
Q: How can I change my vote after I return my Proxy Card?
 
A: You may revoke your proxy and change your vote at any time before the final
    vote at the meeting. You may do this by signing and submitting a new Proxy
    Card with a later date, voting by telephone or using the Internet as
    instructed above (your latest telephone or Internet proxy is counted) or by
    attending the meeting and voting in person. Attending the meeting will not
    revoke your proxy unless you specifically request it.
 
Q: What is Sonus' voting recommendation?
 
A: Our Board of Directors recommends that you vote your shares "FOR" each of the
    nominees to the Board and "FOR" the amendment to the Certificate of
    Incorporation increasing the number of authorized shares of Common Stock and
    the ratification of Arthur Andersen LLP as Sonus' independent auditors for
    fiscal 2001.
 
Q: Where can I find the voting results of the meeting?
 
A: The preliminary voting results will be announced at the meeting. The final
    results will be published in our quarterly report on Form 10-Q for the
    second quarter of fiscal 2001.
 
                                       3

<PAGE>
                                  PROPOSAL ONE
                             ELECTION OF DIRECTORS
 
    Sonus' Board of Directors consists of five members and is divided into three
classes of directors serving staggered three-year terms. Directors for each
class are elected at the annual meeting of shareholders held in the year in
which the term for their class expires. The term for two directors, Paul J.
Ferri and Rubin Gruber will expire at this 2001 Annual Meeting. Each nominee is
presently a director of Sonus. Messrs. Ferri and Gruber, if elected, will serve
a three-year term until Sonus' annual meeting in 2004 or until their respective
successors are elected and qualified. Each of the nominees has consented to
serve a new three-year term. There are no family relationships among our
executive officers and directors.
 
VOTE REQUIRED
 
    The two persons receiving the highest number of votes represented by
outstanding shares of Common Stock present or represented by proxy and entitled
to vote will be elected.
 
    THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR" THE ELECTION TO
THE BOARD OF DIRECTORS OF EACH OF THE FOLLOWING NOMINEES.
 
NOMINEES FOR A THREE-YEAR TERM EXPIRING IN 2004.
 
    PAUL J. FERRI has been a Director since November 1997. Mr. Ferri has been a
general partner of Matrix Partners, a venture capital firm, since 1982. He also
serves on the Board of Directors of Applix, Inc. and Sycamore Networks, Inc.
Mr. Ferri has a B.S. in engineering from Cornell University, an M.S. in
engineering from Polytechnic Institute of New York and an M.B.A. from Columbia
University.
 
    RUBIN GRUBER is one of our founders and has been a Director since
November 1997 and Chairman of our Board of Directors since November 1998. From
November 1997 until November 1998, Mr. Gruber was our President. Before founding
Sonus, Mr. Gruber was a founder of VideoServer, Inc., now Ezenia!, Inc., a
manufacturer of videoconference network equipment, and from February 1992 until
September 1996 served as Vice President of Business Development. Previously,
Mr. Gruber was a founder and served as President of both Cambridge
Telecommunications, Inc., a manufacturer of networking equipment, and Davox
Corporation, a developer of terminals supporting voice and data applications,
and served as a Senior Vice President of Bolt, Beranek and Newman Communications
Corporation, a subsidiary of Bolt, Beranek and Newman, Inc., a manufacturer of
data communications equipment. Mr. Gruber also serves on the Board of Directors
of the International Softswitch Consortium. Mr. Gruber holds a B.Sc. in
mathematics from McGill University and an M.A. in mathematics from Wayne State
University.
 
DIRECTORS WHOSE TERMS WILL EXPIRE IN 2002 AND WHO WILL CONTINUE IN OFFICE FOR
THE REMAINDER OF THEIR TERMS OR EARLIER IN ACCORDANCE WITH SONUS' BY-LAWS.
 
    HASSAN M. AHMED has been our President and Chief Executive Officer and a
member of our Board of Directors since November 1998. From July 1998 to
November 1998, Mr. Ahmed was Executive Vice President and General Manager of the
Core Switching Division of Ascend Communications, Inc., a provider of wide area
network switches and access data networking equipment, and from July 1997 until
July 1998 was a Vice President and General Manager of the Core Switching
Division. From June 1995 to July 1997, Mr. Ahmed was Chief Technology Officer
and Vice President of Engineering for Cascade Communications Corp., a provider
of wide area network switches. From 1993 until June 1995, Mr. Ahmed was a
founder and President of WaveAccess, Inc., a supplier of wireless
communications. Prior to that, he was an Associate Professor at Boston
University, Engineering
 
                                       4

<PAGE>
Manager at Analog Devices, a chip manufacturer, and director of VSLI Systems at
Motorola Codex, a supplier of communications equipment. Mr. Ahmed holds a B.S.
and M.S. in engineering from Carleton University and a Ph.D. in engineering from
Stanford University.
 
    PAUL J. SEVERINO has been a Director since March 1999. Mr. Severino is a
private investor. From 1994 to October 1996, he was Chairman of Bay
Networks, Inc. after its formation from the merger of Wellfleet
Communications, Inc. and Synoptics Communications, Inc. Prior to that, he was a
founder, President and Chief Executive Officer of Wellfleet
Communications, Inc. He also serves on the Board of Directors of
Interspeed, Inc., MCK Communications, Inc., Media 100, Inc., and Silverstream
Software, Inc. Mr. Severino has a B.S. in engineering from Rensselaer
Polytechnic Institute.
 
DIRECTOR WHOSE TERM WILL EXPIRE IN 2003 AND WHO WILL CONTINUE IN OFFICE FOR THE
REMAINDER OF HIS TERM OR EARLIER IN ACCORDANCE WITH SONUS' BY-LAWS.
 
    EDWARD T. ANDERSON has been a Director since November 1997. Mr. Anderson has
been managing general partner of North Bridge Venture Partners, a venture
capital firm, since 1994. Previously, he was a general partner of ABS Ventures,
the venture capital affiliate of Alex Brown & Sons. He has an M.F.A. from the
University of Denver and an M.B.A. from Columbia University.
 
BOARD OF DIRECTORS AND COMMITTEES
 
    The Board of Directors held eight regular meetings during 2000. Each
director attended at least 75% of all board and applicable committee meetings
during 2000. The Board of Directors has two standing committees, the Audit
Committee and the Compensation Committee. Each of these committees are composed
entirely of non-employee directors. The Board of Directors does not have a
nominating committee or a committee serving a similar function; instead the
Board of Directors acts as a whole on such matters.
 
    The Compensation Committee, which consists of Messrs. Ferri and Severino,
reviews executive salaries, administers bonuses, incentive compensation and
stock plans, and approves the salaries and other benefits of our executive
officers. In addition, the compensation committee consults with our management
regarding our benefit plans and compensation policies and practices. There were
four meetings of the Compensation Committee during 2000.
 
    The Audit Committee, which consists of Messrs. Anderson, Ferri and Severino,
reviews the professional services provided by our independent auditors, the
independence of our auditors from our management, our annual financial
statements and our system of internal accounting controls. The audit committee
also reviews other matters with respect to our accounting, auditing and
financial reporting practices and procedures as it may find appropriate or may
be brought to its attention. The members of the Audit Comittee are all
independent, as defined in the National Association of Securities Dealers'
listing standards. There were four meetings of the Audit Committee during 2000.
 
DIRECTOR COMPENSATION
 
    We do not currently compensate our directors in cash for their service as
members of the Board of Directors, although they are reimbursed for reasonable
out-of pocket expenses incurred in connection with attendance at Board of
Director or committee meetings. Under our Amended and Restated 1997 Stock
Incentive Plan, directors are eligible to receive stock option grants or
restricted stock awards at the discretion of the Board of Directors or other
administrator of the Plan. In March 2000, we sold 30,000 shares of restricted
common stock to each of our Directors at a price of $3.33 per share. The
restrictions on the common stock lapse over a four year period, with 25% of the
aggregate number of restricted shares being released from restrictions on
March 9, 2001, and monthly thereafter at the rate of 2.0833% for each month of
service completed.
 
                                       5

<PAGE>
                             COMPENSATION COMMITTEE
 
    COMMITTEE RESPONSIBILITIES.  The Compensation Committee consists of Messrs.
Ferri and Severino. This Committee is responsible for establishing and
monitoring policies governing compensation of executive officers. It has the
responsibility to review the performance and set compensation levels for
executive officers and make option and restricted stock grants to these
individuals under Sonus' 1997 Stock Incentive Plan. The objectives of the
Committee are to correlate executive officer compensation with Sonus' business
objectives, profitability and performance, attract the best talent to Sonus,
motivate individuals to perform at their highest levels, reward outstanding
achievement, and retain those individuals with the leadership abilities and
skills necessary for building long-term shareholder value. The Committee seeks
to reward executives in a manner consistent with Sonus' annual and long-term
performance goals.
 
          COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
    No interlocking relationship exists between any member of our board of
directors or our compensation committee and any member of the board of directors
or compensation committee of any other company, and none of these interlocking
relationships have existed in the past. In March 2000, we sold 30,000 shares of
restricted common stock to each of Messrs. Ferri and Severino at a price of
$3.33 per share under the 1997 Stock Incentive Plan.
 
                        REPORT ON EXECUTIVE COMPENSATION
 
    COMPENSATION PHILOSOPHY.  Since Sonus' inception in 1997, Sonus has sought
to attract, retain and reward executive officers primarily through long-term
equity incentives, in the form of restricted stock awards and stock options. As
a result, the cash component of our executive officers compensation has
reflected base salary and cash-based incentives at lower levels than that of
more established companies in our industry.
 
    BASE SALARY.  Base salaries for fiscal 2000 reflected Sonus' position as an
early stage company. The Committee will review and adjust compensation
appropriately over time in order to compete for and retain executives who
operate Sonus effectively and the Committee plans to continue to align the
interests of Sonus' executive officers with the long-term interests of its
shareholders.
 
    CASH-BASED INCENTIVES.  Sonus made discretionary bonus awards to certain
executives in 2000 based upon their achievement of specified goals. The
Committee believes that a significant portion of each executive officer's
compensation should be tied to the achievement by the Company of its financial
goals and by each executive officer of his or her individual objectives.
Accordingly, cash-based incentives are expected to represent an increasingly
substantive part of total compensation for the Company executives.
 
    EQUITY-BASED INCENTIVES.  The Committee strongly believes in awarding stock
options and restricted stock to Sonus' executive officers to tie executive
officer compensation directly to the long-term success of Sonus and increases in
shareholder value. During fiscal 2000, the Committee granted stock options to
the executive officers to reward the executives for their performance and
establish appropriate incentives.
 
    In determining the size of the stock option grants awarded to each executive
officer in 2000, the Committee took into account the executive officer's
position with Sonus, the executive officer's past performance and the number and
price of unvested options and restricted stock then held by the executive
officer. The Committee expects to apply this criteria to future awards. Stock
options and restricted stock granted to executive officers under Sonus' 1997
Stock Incentive Plan generally have an exercise price equal to the fair market
value on the date of grant and vest over a five- or four-year period, subject to
certain acceleration of vesting upon a change in control of Sonus.
 
                                       6

<PAGE>
    CHIEF EXECUTIVE OFFICER COMPENSATION.  The Chief Executive Officer's
compensation generally is based on the same policies and criteria as the other
executive officers. Mr. Ahmed received a cash bonus for his performance in
fiscal 2000, an additional cash bonus awarded upon the completion of our Initial
Public Offering, and was granted stock options in fiscal 2000. The Compensation
Committee expects to adjust Mr. Ahmed's salary and cash-based incentives in the
future based upon comparative compensation of chief executive officers of
companies of similar magnitude, complexity and scope of responsibility, and
other factors, which may include the financial performance of Sonus and
Mr. Ahmed's success in meeting strategic goals.
 
    POLICY ON DEDUCTIBILITY OF EXECUTIVE COMPENSATION.  The Committee does not
believe Section 162(m) of the Internal Revenue Code of 1986, as amended, which
disallows a tax deduction for certain compensation in excess of $1 million, will
likely have an effect on Sonus in the near future. The Committee believes that
stock options granted under Sonus' 1997 Stock Incentive Plan meet the exception
for qualified performance-based compensation in accordance with Internal Revenue
Code Regulations, so that amounts otherwise deductible with respect to these
options will not count toward the $1 million deduction limit. The Committee's
general policy is to take into account the deductibility of compensation in
determining the type and amount of compensation payable to executive officers.
 
                                          Submitted by,
                                          COMPENSATION COMMITTEE:
                                          Paul J. Ferri
                                          Paul J. Severino
 
                             AUDIT COMMITTEE REPORT
 
    The Audit Committee reviews the financial reporting process, the system of
internal controls, and the audit process. The Audit Committee has adopted a
written charter which has been approved by the Board of Directors, and which is
set forth in Appendix A of this Proxy Statement.
 
    The Audit Committee has reviewed and discussed the Company's audited
financial statements with management, which has primary responsibility for the
financial statements. The Audit Committee has discussed with Arthur Andersen
LLP, Sonus' independent auditors, the matters that are required to be discussed
by Statement of Auditing Standards No. 61 (COMMUNICATION WITH AUDIT COMMITTEES).
The Audit Committee received from Arthur Andersen LLP the written disclosures
required by Independence Standards Board Standard No. l (INDEPENDENCE
DISCUSSIONS WITH AUDIT COMMITTEES), and discussed with Arthur Andersen LLP their
independence.
 
    Based on the review and discussions noted above, the Audit Committee
recommended to the Board of Directors, and the Board has approved, that the
audited financial statements be included in Sonus' Annual Report on Form 10-K
for the year ended December 31, 2000, for filing with the Securities and
Exchange Commission, and that Arthur Andersen LLP be appointed independent
auditors for the Company for 2001.
 
                                          Submitted by,
                                          AUDIT COMMITTEE:
                                          Edward T. Anderson
                                          Paul J. Ferri
                                          Paul J. Severino
 
                                       7

<PAGE>
EXECUTIVE OFFICERS AND DIRECTORS
 
    The following table sets forth our executive officers and directors, their
respective ages and positions as of February 15, 2001:
 

<TABLE>
<CAPTION>
NAME                              AGE      POSITION
----                            --------   --------
<S>                             <C>        <C>
Rubin Gruber..................  56         Chairman of the Board of Directors
Hassan M. Ahmed...............  43         President, Chief Executive Officer and Director
Anousheh Ansari...............  34         Vice President and General Manager of IntelligentIP Division
Stephen A. Collins............  41         Vice President of Marketing
Michael G. Hluchyj............  46         Chief Technology Officer, Vice President and Secretary
Paul R. Jones.................  51         Vice President of Engineering
Jeffrey Mayersohn.............  49         Vice President of Customer Support and Professional
                                           Services
Stephen J. Nill...............  49         Chief Financial Officer, Vice President of Finance and
                                           Administration and Treasurer
Gary A. Rogers................  45         Vice President of Worldwide Sales
Frank T. Winiarski............  58         Vice President of Manufacturing
Edward T. Anderson............  51         Director
Paul J. Ferri.................  62         Director
Paul J. Severino..............  54         Director
</TABLE>

 
------------------------
 
RUBIN GRUBER--See "PROPOSAL ONE--ELECTION OF DIRECTORS" for Mr. Gruber's
background.
 
HASSAN M. AHMED--See "PROPOSAL ONE--ELECTION OF DIRECTORS" for Mr. Ahmed's
background.
 
ANOUSHEH ANSARI has been our Vice President and General Manager of the
IntelligentIP Division since our acquisition of TELECOM TECHNOLOGIES, INC. (TTI)
in January 2001. Ms. Ansari was a founder, Chairman of the Board of Directors
and Chief Executive Officer of TTI. Prior to founding TTI in 1993, Ms. Ansari
provided consulting services to major telecommunications service providers and
held positions with both MCI Telecommunications Corporation and Communication
Satellite Corporation. Ms. Ansari holds a B.S. in electrical engineering from
George Mason University and an M.S. in electrical engineering from George
Washington University.
 
STEPHEN A. COLLINS has been our Vice President of Marketing since
December 2000. From September 2000 until December 2000, he was Vice President of
Business Development at Lucent Technologies. From March 1998 until
September 2000, Mr. Collins was a founder and served as Vice President of
Marketing and Business Development of Spring Tide Networks, Inc., a provider of
carrier-class solutions. From April 1996 to December 1997, he was the Vice
President of Marketing at StarBurst Communications Corporation, a data delivery
software company, and from October 1994 to March 1996 he was Director of Product
Marketing at Bay Networks, Inc., a provider of internetworking communications
products. Mr. Collins holds a B.S. in computer engineering from the University
of Massachusetts and an M.S. in computer engineering from the University of
Michigan.
 
MICHAEL G. HLUCHYJ is one of our founders and has been our Chief Technology
Officer and Vice President since November 1997. He also has been our Secretary
since our inception, our President from August 1997 to November 1997, our
Treasurer from inception until March 2000 and a Director from our inception
until November 1998. From July 1994 until July 1997, he was Vice President and
Chief Technology Officer at Summa Four, Inc., a supplier of switches for carrier
networks. Previously, he was Director of Networking Research at Motorola Codex
and on the technical staff at AT&T Bell Laboratories. Mr. Hluchyj holds a B.S.
in engineering from the University of Massachusetts and an M.S. and a Ph.D. in
engineering from the Massachusetts Institute of Technology.
 
                                       8

<PAGE>
PAUL R. JONES has been our Vice President of Engineering since June 2000. From
February 1997 until May 2000, he was Vice President of Engineering for Indus
River Networks, Inc., a developer of virtual private network solutions. From
December 1994 until February 1996, he was Chief Operating Officer at Isis
Distribution Systems, a wholly owned subsidiary of Stratus Computers. From
March 1990 until November 1994, he was Vice President of Engineering at Stratus
Computers, Inc., a provider of fault tolerant computer systems and services.
Previously, Mr. Jones held senior engineering management positions at Stellar
Computers, Inc. and Prime Computer, Inc. Mr. Jones holds an A.B. from Brown
University and an M.S. in engineering from the University of Massachusetts.
 
JEFFREY MAYERSOHN has been our Vice President of Customer Support and
Professional Services since July 1999. From March 1998 until July 1999, he was
our Vice President of Carrier Relations. From June 1997 to March 1998,
Mr. Mayersohn was a Senior Vice President at GTE Internetworking, an Internet
service provider. From January 1995 to June 1997, he was with BBN Corporation,
formerly Bolt, Beranek and Newman, Inc., and was a Vice President at the BBN
Planet division, an Internet service provider. From 1978 to January 1995, he
held a number of positions at Bolt, Beranek and Newman Communications
Corporation, including Senior Vice President of Engineering, Senior Vice
President responsible for U.S. Government Networks and Vice President of
Professional Services. Mr. Mayersohn holds an A.B. in physics from Harvard
College and an M.Phil. in physics from Yale University.
 
STEPHEN J. NILL has been our Chief Financial Officer and Vice President of
Finance and Administration since September 1999 and our Treasurer since
March 2000. From June 1994 until August 1999, he was Vice President of Finance
and Chief Financial Officer of VideoServer, Inc., now Ezenia!, Inc. Previously,
he served as Corporate Controller and Chief Accounting Officer at Lotus
Development Corporation, a software supplier. Prior to that, Mr. Nill held
various financial positions with Computervision, Inc., a supplier of
workstation-based software, International Business Machines Corporation and
Arthur Andersen LLP. Mr. Nill has a B.A. in accounting from New Mexico State
University and an M.B.A. from Harvard University.
 
GARY A. ROGERS has been our Vice President of Worldwide Sales since March 1999.
From March 1999 to December 2000, Mr. Rogers was also our Vice President of
Marketing. From February 1997 to March 1999, Mr. Rogers was Senior Vice
President of Worldwide Sales and Operations at Security Dynamics, Inc., now RSA
Security, Inc., a supplier of network security products. Previously, he served
at Bay Networks, Inc., as Vice President of International Sales from July 1996
to February 1997 and as Vice President of Europe, Middle East and Africa from
1994 until July 1996. Prior to that, he held sales and marketing positions with
International Business Machines Corporation. Mr. Rogers holds a B.S. in
mathematics from Dartmouth College and an M.B.A. from the University of Chicago.
 
FRANK T. WINIARSKI has been our Vice President of Manufacturing since
July 1998. From June 1997 until June 1998, he was Vice President of
Manufacturing at Net2Net, Inc., a supplier of network analyzers. From June 1992
until June 1997, he was Vice President of Manufacturing at VideoServer, Inc.,
now Ezenia!, Inc. Previously, Mr. Winiarski was Vice President of Manufacturing
at Synernetics, a supplier of local area networks, Vice President of Operations
at Ashton-Tate Corporation, a software supplier, and held various positions with
Digital Equipment Corporation, a computer equipment manufacturer. Mr. Winiarski
holds a B.S. in engineering from the University of Idaho and an M.B.A. from
Boston University.
 
EDWARD T. ANDERSON--See "PROPOSAL ONE--ELECTION OF DIRECTORS" for
Mr. Anderson's background.
 
PAUL J. FERRI--See "PROPOSAL ONE--ELECTION OF DIRECTORS" for Mr. Ferri's
background.
 
PAUL J. SEVERINO--See "PROPOSAL ONE--ELECTION OF DIRECTORS" for Mr. Severino's
background.
 
                                       9

<PAGE>
BENEFICIAL OWNERSHIP
 
    The following table sets forth information regarding beneficial ownership of
our Common Stock as of February 15, 2001 by:
 
    - each person who beneficially owns, to the best of our knowledge, more than
      5% of the outstanding shares of our Common Stock;
 
    - each of our executive officers listed in the Summary Compensation Table on
      page 13;
 
    - each of our directors; and
 
    - all of our executive officers and directors as a group.
 
Beneficial ownership is determined in accordance with the rules of the
Securities and Exchange Commission, and includes voting and investment power
with respect to shares. Unless otherwise indicated below, to our knowledge, all
persons named in the table have sole voting and investment power with respect to
their shares of Common Stock, except to the extent authority is shared by
spouses under applicable law. The percentage of Common Stock outstanding as of
February 15, 2001 is based on 202,286,745 shares of Common Stock outstanding on
that date. Unless otherwise indicated, the address of each listed shareholder is
care of Sonus Networks, Inc., 5 Carlisle Road, Westford, Massachusetts 01886.
 

<TABLE>
<CAPTION>
                                                              NUMBER OF SHARES    PERCENTAGE
NAME OF BENEFICIAL OWNER                                     BENEFICIALLY OWNED   OUTSTANDING
------------------------                                     ------------------   -----------
<S>                                                          <C>                  <C>
EXECUTIVE OFFICERS AND DIRECTORS:
Anousheh Ansari(1).........................................      13,314,439           6.6%
Hassan M. Ahmed(2).........................................       9,532,309           4.7%
Paul J. Ferri(3)...........................................       8,777,028           4.3%
Michael G. Hluchyj(4)......................................       6,742,910           3.3%
Rubin Gruber(5)............................................       3,852,533           1.9%
Edward T. Anderson(6)......................................       1,881,256             *
Gary A. Rogers(7)..........................................       1,789,312             *
Stephen J. Nill(8).........................................       1,540,760             *
Paul J. Severino(9)........................................         556,442             *
All executive officers and directors as
  a group (13 persons)(10).................................      50,467,642          24.9%
 
5% OWNERS:
Putnam Investments, LLC and affiliated entities(11)........      10,653,795           5.3%
FMR Corp. and affiliated entities(12)......................      10,483,670           5.2%
</TABLE>

 
------------------------
 
* Less than 1% of the outstanding shares of Common Stock.
 
(SEE THE FOOTNOTES ON THE FOLLOWING PAGE)
 
                                       10

<PAGE>
 (1) Includes 1,440,000 shares held by Ansari AA Investments, Ltd., 288,000
     shares held by Ansari AR Investments, Ltd., 192,000 shares held by Ansari
     JA Investments, Ltd. and 288,000 shares held by Cedar Grantor Retained
     Annuity Trust over which Ms. Ansari has sole voting and investment power.
     Includes 5,506,197 shares issued to Ms. Ansari, her husband Hamid Ansari
     and those entities listed in the prior sentence in connection with our
     acquisition of TTI, of which 1,100,000 were issued under our 2000 Retention
     Plan and are escrowed and subject to vesting, 979,155 are escrowed to
     secure indemnity obligations and 3,427,042 are escrowed and subject to
     release upon completion of specified business milestones. Also, includes
     1,365,684 shares issued to Ms. Ansari that are pledged to Sonus to satisfy
     obligations under her employment agreement and 1,548,340 shares issued to
     Ms. Ansari that will be returned to Sonus upon the exercise of options
     outstanding under TTI's 1998 Equity Incentive Plan ("the 1998 Plan"), as
     described in the following sentence. In continuation of a 1997 Agreement
     entered into by Ms. Ansari and Hamid Ansari and other then-shareholders of
     TTI, the Ansari's have agreed, from time to time, to transfer to us in
     exchange for the option exercise proceeds, a number of shares of our Common
     Stock received by them in connection with the TTI acquisition equal to the
     number of shares of our Common Stock issued upon exercise of the stock
     options granted under the 1998 Plan that were assumed by Sonus. As a result
     of this agreement, the aggregate number of outstanding shares of our common
     stock that will be issued upon exercise of these stock options would not
     increase but Ms. Ansari's aggregate holdings will decrease.
 
 (2) Includes 5,440,939 shares that are subject to our right to repurchase at
     cost if Mr. Ahmed ceases to be employed by us. Includes 2,906,000 shares
     held by family trusts and by his minor children. Mr. Ahmed disclaims
     beneficial ownership of the shares held by these trusts.
 
 (3) Composed of 7,779,291 shares held by Matrix Partners V, L.P., 894,469
     shares held by Matrix V Entrepreneurs Fund, L.P., 73,268 shares held by
     Mr. Ferri and includes 30,000 shares which are subject to our right to
     repurchase at cost if Mr. Ferri ceases to serve as one of our directors.
     Matrix V Management Co., L.L.C. is the general partner of the
     aforementioned entities. Paul J. Ferri is a director of Sonus and is a
     general partner of Matrix V Management Co., L.L.C. Mr. Ferri disclaims
     beneficial ownership of the shares held by these entities except to the
     extent of his proportionate pecuniary interest therein. Mr. Ferri, by
     virtue of his management position in the Matrix entities, has sole voting
     and dispositive power with respect to the shares owned by Matrix Partners
     V, L.P. and Matrix V Entrepreneurs Fund, L.P. The address of Mr. Ferri is
     in care of Matrix V Management Co., L.L.C., 1000 Winter Street, Suite 4500,
     Waltham, MA 02451.
 
 (4) Includes 1,566,094 shares that are subject to our right to repurchase at
     cost if Mr. Hluchyj ceases to be employed by us. Includes an aggregate of
     2,115,000 shares held by family trusts and by his minor children.
     Mr. Hluchyj disclaims beneficial ownership of the shares held by these
     trusts and his minor children.
 
 (5) Includes 1,271,701 shares that are subject to our right to repurchase at
     cost if Mr. Gruber ceases to be employed by us.
 
 (6) Composed of 1,611,180 shares held by Mr. Anderson, 240,076 shares held by
     family trusts and includes 30,000 shares that are subject to our right to
     repurchase at cost if Mr. Anderson ceases to serve as one of our directors.
     Mr. Anderson is a director of Sonus and disclaims beneficial ownership of
     the shares held by these trusts. The address of Mr. Anderson is in care of
     North Bridge Ventures L.P., 950 Winter Street, Suite 4600, Waltham, MA
     02451.
 
 (7) Includes 1,296,750 shares that are subject to our right to repurchase at
     cost if Mr. Rogers ceases to be employed by us. Includes 900,000 shares
     held by a family trust and 12,000 shares held in trust for his minor
     children. Mr. Rogers disclaims beneficial ownership of the shares held by
     these trusts.
 
                                       11

<PAGE>
 (8) Includes 1,209,375 shares that are subject to our right to repurchase at
     cost if Mr. Nill ceases to be employed by us. Includes 390,000 shares held
     by a family trust, of which Mr. Nill disclaims beneficial ownership.
 
 (9) Includes 30,000 shares that are subject to our right to repurchase at cost
     if Mr. Severino ceases to serve as one of our directors. Includes 51,000
     shares held for the benefit of Mr. Severino's minor child under the
     Massachusetts Uniform Transfer to Minors Act.
 
(10) Includes 12,167,358 shares that are subject to our right to repurchase at
     cost if our executive officers cease to be employed by us or our directors
     cease to serve as directors and includes 7,054,537 issued shares that are
     escrowed or subject to vesting.
 
(11) At February 15, 2001, (i) Putnam Investment Management, LLC., a wholly
     owned subsidiary of Marsh & McLennan Companies, Inc., was the beneficial
     owner of 9,918,495 shares of common stock in its capacity as investment
     adviser to the Putnam family of mutual funds; and (ii) Putnam Advisory
     Company, LLC., was the beneficial owner of 735,300 shares of common stock
     in its capacity as investment adviser to the Putnam's institutional
     clients. Both subsidiaries have dispository power over the shares as
     investment managers, but each of the mutual fund's trustees have voting
     power over the shares held by each fund and The Putnam Advisory Company,
     LLC. has shared voting power over the shares held by the institutional
     clients.
 
(12) At February 15, 2001, (i) Fidelity Management & Research Company, a wholly
     owned subsidiary of FMR Corp., was the beneficial owner of 9,928,810 shares
     of common stock in its capacity as investment adviser to various registered
     investment companies (the power to vote such shares resides solely with the
     boards of trustees of these Fidelity funds, while the power to dispose of
     such shares resides with Edward C. Johnson 3rd, FMR Corp., Fidelity and the
     Fidelity funds); (ii) Fidelity Management Trust Company, a bank that is
     wholly owned by FMR Corp., was the beneficial owner of 438,360 shares of
     common stock; and (iii) Fidelity International Limited, an investment
     adviser of which Mr. Johnson is chairman but which is managed independently
     from FMR Corp., was the beneficial owner of 116,500 shares of common stock.
     FMR Corp. and Fidelity International Limited each disclaim beneficial
     ownership of common stock beneficially owned by the other. According to the
     Schedule 13G filed with the Securities and Exchange Commission jointly by
     FMR Corp., Mr. Johnson and Abigail P. Johnson, Mr. Johnson is chairman and
     Ms. Johnson is a director of FMR Corp. and may be deemed to be members of a
     controlling group with respect to FMR Corp.
 
                                       12

<PAGE>
                             EXECUTIVE COMPENSATION
 
    The following table sets forth, for the years ended December 31, 1999 and
2000, the compensation earned by our Chairman of the Board of Directors, our
Chief Executive Officer, and the other three most highly compensated executive
officers who received annual compensation in excess of $100,000.
 
                           SUMMARY COMPENSATION TABLE
 

<TABLE>
<CAPTION>
                                                                                                     LONG-TERM
                                                                                                COMPENSATION AWARDS
                                                               ANNUAL COMPENSATION           -------------------------
                                                        ----------------------------------   RESTRICTED    SECURITIES
                                                                               ALL OTHER       STOCK       UNDERLYING
NAME AND PRINCIPAL POSITION                    YEAR      SALARY     BONUS     COMPENSATION   AWARDS(5)    OPTIONS/SARS
---------------------------                  --------   --------   --------   ------------   ----------   ------------
<S>                                          <C>        <C>        <C>        <C>            <C>          <C>
Rubin Gruber...............................    2000     $150,000   $    --      $     --     $      0(6)    888,000
  Chairman of the Board of Directors           1999      150,000        --            --           --            --
 
Hassan M. Ahmed............................    2000      150,000    75,000       313,000(2)         0(6)    813,000
  President and Chief Executive Officer        1999      150,000    75,000        36,417(2)        --
 
Michael G. Hluchyj.........................    2000      150,000        --            --           --       723,000
  Chief Technology Officer, Vice               1999      150,000        --            --           --            --
  President and Secretary
 
Stephen J. Nill............................    2000      150,000        --        50,000(3)         0(6)    138,000
  Chief Financial Officer, Vice                1999       43,269(1)      --           --            0(7)         --
  President of Finance and
  Administration and Treasurer
 
Gary A. Rogers.............................    2000      144,940        --       605,832(4)         0(6)     39,000
  Vice President of Worldwide Sales            1999      111,371(1)               99,107(4)         0(7)         --
</TABLE>

 
--------------------------
 
(1) Represents the total amount of compensation received in fiscal 1999 for the
    portion of the year during which he was one of our executive officers.
    Messrs. Rogers and Nill joined us in March and September of 1999,
    respectively.
 
(2) Represents amounts due in connection with original employment, including, in
    2000, $275,000 due upon the completion of our initial public offering.
 
(3) Represents amounts due upon completion of one year of service.
 
(4) Represents commission income.
 
(5) On December 31, 2000, the remaining number of shares of restricted Common
    Stock held by the above executive officers that had not vested and the value
    of this stock as of December 31, 2000, was as follows: Mr. Gruber: 1,311,281
    shares, $33,108,097; Mr. Ahmed: 5,600,977 shares, $141,237,970;
    Mr. Hluchyj: 1,686,563 shares, $42,858,491; Mr. Nill: 1,249,500 shares,
    $31,466,575; and Mr. Rogers: 1,359,000 shares, $34,224,150. The value is
    based on the fair market value of Sonus' Common Stock on December 31, 2000
    of $25.25 per share less the purchase price paid. The holders of these
    shares of restricted Common Stock will be entitled to receive any dividends
    we pay on our Common Stock.
 
(6) In March 2000, we sold shares of restricted Common Stock to the above
    executive officers as follows: Mr. Gruber: 75,000 shares; Mr. Ahmed: 150,000
    shares; Mr. Nill: 30,000 shares; and Mr. Rogers: 150,000 shares. These
    shares of restricted Common Stock are subject to our right to repurchase at
    $3.33 per share, the then current fair market value of the Common Stock as
    determined by our Board of Directors. Our repurchase rights generally lapse
    one year from the date of the purchase. There was no public trading market
    for the Common Stock in March 2000. Our Board of Directors determined the
    fair market value of the Common Stock based on various factors including the
    illiquid nature of an investment in our Common Stock, our historical
    performance, the preferences, including liquidation and redemption of our
    outstanding redeemable convertible preferred stock, our future prospects and
    the prices of our securities sold in arm's-length transactions to third
    parties.
 
(SEE THE FOOTNOTES ON THE FOLLOWING PAGE)
 
                                       13

<PAGE>
(7) In April and September of 1999, we sold 1,875,000 and 1,687,500 shares of
    restricted Common Stock to Messrs. Rogers and Nill, respectively, subject to
    our right to repurchase at $0.07 per share, the then-current fair market
    value of the Common Stock as determined by our Board of Directors. Our
    repurchase right lapses 20% one year from the date Messrs. Rogers and Nill
    each commenced employment and thereafter lapses for an additional 1.6667% of
    the shares for each month of employment. There was no public trading market
    for the Common Stock in April and September of 1999. Our Board of Directors
    determined the market value of the Common Stock based on various factors
    including the illiquid nature of an investment in our Common Stock, our
    historical performance, the preferences, including liquidation and
    redemption of our outstanding redeemable convertible preferred stock, our
    future prospects and the price of our securities sold in arm's-length
    issuances to third parties.
 
                       OPTION GRANTS IN LAST FISCAL YEAR
 
    The Option Grant Table below sets forth hypothetical gains or "option
spreads" for the options at the end of their respective ten-year terms, as
calculated in accordance with the rules of the Securities and Exchange
Commission. Each gain is based on an arbitrarily assumed annualized rate of
compound appreciation of the market price at the date of grant of 5% and 10%
from the date the option was granted to the end of the option term. Actual
gains, if any, on option exercises are dependent on the future performance of
our Common Stock and overall market conditions.
 

<TABLE>
<CAPTION>
                                                  PERCENT OF                              POTENTIAL REALIZABLE VALUE AT
                                      NO. OF     TOTAL OPTIONS                               ASSUMED ANNUAL RATES OF
                                    SECURITIES    GRANTED TO                                 STOCK APPRECIATION FOR
                                    UNDERLYING     EMPLOYEES     EXERCISE                        OPTION TERM(4)
                                     OPTIONS        DURING       PRICE PER   EXPIRATION   -----------------------------
NAME                                GRANTED(1)     PERIOD(2)     SHARE(3)       DATE           5%              10%
----                                ----------   -------------   ---------   ----------   -------------   -------------
<S>                                 <C>          <C>             <C>         <C>          <C>             <C>
Rubin Gruber......................    888,000        5.72%         $3.33      3/9/2010     $1,859,667      $4,712,760
Hassan M. Ahmed...................    813,000        5.23           3.33      3/9/2010      1,702,600       4,314,723
Michael G. Hluchyj................    723,000        4.65           3.33      3/9/2010      1,514,120       3,837,078
Stephen J. Nill...................    138,000        0.89           3.33      3/9/2010        289,002         732,388
Gary A. Rogers....................     39,000        0.25           3.33      3/9/2010         81,675         206,979
</TABLE>

 
------------------------
 
(1) Generally, these options vest up to 25% one year from the date of grant and
    thereafter an additional 2.0833% for each month of employment.
 
(2) Based on an aggregate of 15,531,937 options granted by Sonus to employees
    and consultants, including the executive officers named in the Summary
    Compensation Table during the fiscal year ended December 31, 2000.
 
(3) Options were granted with an exercise price equal to the fair market value
    of our Common Stock, as determined in good faith by our Board of Directors.
 
(4) The potential realizable value is calculated based on (a) the ten-year term
    of the option at its time of grant; (b) the assumption that the closing
    price for the Common Stock on the date of grant appreciates at the indicated
    annual rate compounded annually for the entire term of the option; and
    (c) the assumption that the option is exercised and sold on the last day of
    its term for the appreciated stock price.
 
                                       14

<PAGE>
                         FISCAL YEAR-END OPTION VALUES
 
    The following table presents the value of unexercised stock options as of
December 31, 2000, held by our executive officers listed in the Summary
Compensation Table. No options were exercised during fiscal year 2000 by any of
these executive officers.
 

<TABLE>
<CAPTION>
                                                    NUMBER OF SECURITIES
                                                   UNDERLYING UNEXERCISED         VALUE OF UNEXERCISED
                                                         OPTIONS AT              IN-THE-MONEY OPTIONS AT
                                                      DECEMBER 31, 2000           DECEMBER 31, 2000(1)
                                                 ---------------------------   ---------------------------
NAME                                             EXERCISABLE   UNEXERCISABLE   EXERCISABLE   UNEXERCISABLE
----                                             -----------   -------------   -----------   -------------
<S>                                              <C>           <C>             <C>           <C>
Rubin Gruber...................................          --       888,000      $       --     $19,464,960
Hassan M. Ahmed................................          --       813,000              --      17,820,960
Michael G. Hluchyj.............................          --       723,000              --      15,848,160
Stephen J. Nill................................          --       138,000              --       3,024,960
Gary A. Rogers.................................          --        39,000              --         854,880
</TABLE>

 
------------------------
 
(1) The value of in-the-money options is based on the closing price of our
    Common Stock on December 31, 2000 of $25.25 per share, minus the per share
    exercise price, multiplied by the number of shares underlying the option.
 
                              EMPLOYMENT AGREEMENT
 
    In connection with our acquisition of TELECOM TECHNOLOGIES, INC. or TTI, we
entered into an employment agreement with Anousheh Ansari, formerly the Chairman
and Chief Executive Officer of TTI. The term of this employment agreement began
on January 18, 2001 and continues until January 1, 2003. Under this agreement,
Ms. Ansari became a Sonus senior executive with the title of Vice President and
General Manager of our INtelligentIP Division.
 
    During the employment period, Ms. Ansari will receive a minimum annual base
salary of $150,000 per year, and an annual cash bonus to be determined on the
same basis as we determine annual bonuses, if any, for our other senior
executives. In addition, as of January 18, 2001, we granted Ms. Ansari a
retention stock award of 550,000 shares of our Common Stock under our 2000
Retention Plan. Ms. Ansari is entitled to participate in all employee benefit,
welfare, performance, fringe benefit and other plans, practices, policies and
programs applicable to our senior executives.
 
    In the event we terminate Ms. Ansari's employment other than for cause or
disability, or Ms. Ansari terminates her employment for good reason, Ms. Ansari
will receive:
 
    - an immediate lump-sum payment equal to the sum of (1) Ms. Ansari's annual
      base salary earned through the date of termination; (2) any bonus amounts
      earned but unpaid with respect to a calendar year ending prior to the date
      of termination; and (3) any compensation previously deferred by
      Ms. Ansari, together with accrued interest thereon, in each case to the
      extent not already paid;
 
    - any additional severance amounts and benefits payable to our senior
      executives in accordance with our most favorable policies and procedures,
      or, if greater, an immediate lump-sum payment equal to Ms. Ansari's annual
      base salary for the remainder of the employment term; and
 
    - the retention stock award described above will immediately and fully vest
      and become free of restrictions without regard to the achievement of the
      business expansion and product development milestones under our 2000
      Retention Plan, and any lock-up agreement with respect to shares of our
      Common Stock that may have been entered into under the registration rights
      agreement entered into with the former TTI shareholders will expire.
 
                                       15

<PAGE>
    Ms. Ansari has agreed that, in the event she terminates her employment on or
before January 1, 2003 without good reason, or we terminate her employment on or
before January 1, 2003 for cause, she will make a payment to us. This payment
will be $35.0 million if her employment terminates on or prior to July 19, 2002
and will thereafter decline by $5.0 million per month. Any payment made by Hamid
Ansari, formerly the President of TTI, under a similar provision in his
employment agreement is to be credited against any payment that may become due
by Ms. Ansari. Ms. Ansari has pledged 1,365,684 shares of Common Stock to Sonus
pursuant to her employment agreement to secure this payment obligation.
 
    Under the terms of the employment agreement, Ms. Ansari has agreed that for
the employment period and for an additional period ending on the later of
(1) two years after her termination of employment during the employment period
and (2) January 18, 2005, she will not, directly or indirectly, compete with us
or recruit, hire or solicit any of our employees, other than Hamid Ansari.
Ms. Ansari has also agreed not to disclose any confidential information of Sonus
to any person other than employees of Sonus or use that information for any
purpose other than the performance of her duties as an employee of Sonus.
 
CERTAIN TRANSACTIONS
 
    In March 2000, we granted options to purchase shares of our Common Stock and
the right to purchase restricted Common Stock to our executive officers and
non-employee directors, under our 1997 Stock Incentive Plan, each at a price of
$3.33 per share, as listed below:
 

<TABLE>
<CAPTION>
                                                                NUMBER         NUMBER OF
                                                              OF OPTIONS   RESTRICTED SHARES
NAME                                                           GRANTED         PURCHASED
----                                                          ----------   -----------------
<S>                                                           <C>          <C>
Rubin Gruber................................................    888,000          75,000
Hassan M. Ahmed.............................................    813,000         150,000
Michael G. Hluchyj..........................................    723,000              --
Jeffrey Mayersohn...........................................    168,750          56,250
Stephen J. Nill.............................................    138,000          30,000
Gary A. Rogers..............................................     39,000         150,000
Frank T. Winiarski..........................................         --          75,000
Edward T. Anderson..........................................         --          30,000
Paul J. Ferri...............................................         --          30,000
Paul J. Severino............................................         --          30,000
</TABLE>

 
    In May 2000, we granted an option to purchase 450,000 shares of our Common
Stock to Paul R. Jones, our Vice President of Engineering, under our 1997 Stock
Incentive Plan, at an exercise price of $4.67 per share.
 
    In December 2000, we granted an option to purchase 300,000 shares of our
Common Stock to Stephen A. Collins, our Vice President of Marketing, under our
1997 Stock Incentive Plan, at an exercise price of $22.25 per share.
 
    The options described in the preceding paragraphs vest, and the restrictions
on the Common Stock lapse, over a four-year period with 25% of the aggregate
number of options and restricted shares vesting, or being released from
restrictions, one year from the date of grant and monthly thereafter at the rate
of 2.0833% for each month of employment or service completed by the executive
officer or non-employee director.
 
                                       16

<PAGE>
AGREEMENTS WITH EXECUTIVE OFFICERS
 
    On November 4, 1998, in connection with the issuance of restricted Common
Stock, we loaned $257,000 to Hassan M. Ahmed, our President and Chief Executive
Officer. The loan was secured by 7,710,000 shares of our restricted Common Stock
and bears interest at 8% per year. In connection with the consummation of our
initial public offering, we agreed to pay Mr. Ahmed $275,000. As of March 31,
2001, the loan has been fully repaid.
 
    On September 1, 1999, in connection with the issuance of restricted Common
Stock, we loaned $110,250 to Stephen J. Nill, our Chief Financial Officer, Vice
President of Finance and Administration and Treasurer. The loan was secured by
1,687,500 shares of his Common Stock and was a full recourse note, bearing
interest at 8% per year. As of December 31, 2000, the loan has been fully
repaid.
 
    We believe that all of the transactions set forth above were made on terms
no less favorable to us than could have been obtained from unaffiliated third
parties. All future transactions, including loans between us and our officers,
directors, principal shareholders and their affiliates will be approved by a
majority of the Board of Directors, including a majority of the independent and
disinterested directors on the Board of Directors, and will be on terms no less
favorable to us than could be obtained from unaffiliated third parties. See
"Employment Agreement" for a description of our employment agreement with
Ms. Anousheh Ansari, our Vice President and General Manager of our INtelligentIP
division.
 
                            STOCK PERFORMANCE GRAPH
 
    The following performance graph show the eight-month cumulative total
shareholder return assuming the investment of $100 on May 25, 2000 (the date of
Sonus' initial public offering) in Sonus Common Stock, the Nasdaq Composite
Index and the Nasdaq Telecommunications Index. The performance shown is not
necessarily indicative of future performance.
 
EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC
 

<TABLE>
<CAPTION>
               SONUS   COMPOSITE  TELECOMM
<S>           <C>      <C>        <C>
May-00            100        100       100
June-00       $312.63    $123.73   $123.26
September-00  $250.25    $114.58   $103.33
December-00   $150.00     $77.07    $65.61
</TABLE>

 
                                       17

<PAGE>
                                  PROPOSAL TWO

                 AMENDMENT TO THE CERTIFICATE OF INCORPORATION
 
    On March 15, 2001, Sonus' Board of Directors unanimously approved an
amendment to the Amended and Restated Certificate of Incorporation to permit
Sonus to issue up to 600,000,000 shares of Common Stock. The Board directed that
the amendment be voted on by shareholders. Currently, 300,000,000 shares of
Common Stock are authorized of which as of February 15, 2001, approximately
254,700,000 shares are outstanding or are reserved for future issuance:
 
    - 202,300,000 shares are outstanding;
 
    - 17,500,000 shares are reserved for issuance upon exercise of outstanding
      stock options;
 
    - 28,100,000 shares are reserved for issuance under our incentive stock
      plan; and
 
    - 6,800,000 shares are reserved for future issuances under our employee
      stock purchase plan.
 
    As of February 15, 2001, Sonus has approximately 45,300,000 shares available
for issuance.
 
                            PURPOSE OF THE AMENDMENT
 
    The Board desires to increase the number of shares of Common Stock that
Sonus can issue for possible stock splits, acquisitions, financings, and other
corporate purposes. The Board believes that stock splits enhance the liquidity
and marketability of the Common Stock by increasing the number of shares
outstanding and lowering the price per share. The Board approved a three-for-one
stock split that was effected in October 2000.
 
    Having this additional authorized Common Stock available for issuance in the
future would allow the Board of Directors to issue shares of Common Stock
without the delay and expense associated with the necessity of obtaining prior
shareholder approval. Elimination of this delay will better enable us to engage
in financing transactions and mergers and acquisitions on an opportunistic and
more competitive basis as market and financial conditions continue to change.
Sonus does not currently plan to issue any of the additional shares of Common
Stock.
 
                       POSSIBLE EFFECTS OF THE AMENDMENT
 
    If the proposed amendment is approved, the Board of Directors may cause the
issuance of additional shares of Common Stock without the further vote of
shareholders of Sonus, except as provided under Delaware corporate law or under
the rules of any securities market on which shares of Common Stock are then
traded.
 
    Current holders of Common Stock have no pre-emptive or similar rights, which
means that current shareholders do not have a prior right to purchase any new
issue of Common Stock of Sonus in order to maintain their proportionate
ownership. The effects of the authorization of additional shares of Common Stock
may also include dilution of the voting power of currently outstanding shares.
Future issuances of additional authorized shares of Common Stock may, among
other things, have a dilutive effect on earnings per share of the Common Stock.
 
    In addition, the Board of Directors could use authorized but unissued shares
to create impediments to a takeover or a transfer of control of Sonus.
Accordingly, an effect of the increase in the number of authorized shares of
Common Stock may be to deter a future takeover attempt which holders of Common
Stock may deem to be in their best interest or in which holders of Common Stock
may be offered a premium for their shares over the market price.
 
    The Board of Directors is not currently aware of any attempt to take over or
acquire Sonus. While it may be deemed to have potential anti-takeover effects,
the proposed amendment to increase the
 
                                       18

<PAGE>
authorized Common Stock is not prompted by any specific effort or takeover
threat currently perceived by management. Moreover, management does not
currently intend to propose anti-takeover measures in the foreseeable future.
 
    THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR" THE AMENDMENT TO
OUR CERTIFICATE OF INCORPORATION TO INCREASE THE NUMBER OF AUTHORIZED SHARES OF
COMMON STOCK FROM 300,000,000 TO 600,000,000 SHARES.
 
                                 PROPOSAL THREE
                      RATIFICATION OF INDEPENDENT AUDITORS
 
    The Board of Directors has appointed Arthur Andersen, LLP as Sonus'
independent auditors for the current fiscal year. Arthur Andersen has served as
auditors for Sonus since 1998. Fees paid to the independent auditors were as
follows: Audit Fees: $137,000 for the audit of the consolidated financial
statements for the fiscal year ended December 31, 2000 and for the review of the
consolidated financial statements included in the Company's quarterly filings on
Form 10-Q; and Other Fees: $320,000 for audit-related services. Audit related
services generally include fees for business acquisitions, accounting
consultations and SEC registration statements. Representatives of Arthur
Andersen LLP are expected to attend the meeting, where they will be available to
respond to questions and, if they desire, to make a statement.
 
    THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR" RATIFICATION OF
THE APPOINTMENT OF ARTHUR ANDERSEN LLP AS OUR INDEPENDENT AUDITORS FOR THE 2001
FISCAL YEAR.
 
BENEFICIAL OWNERSHIP COMPLIANCE
 
    To the knowledge of Sonus, based solely on a review of the copies of reports
furnished to Sonus, Sonus believes that during the year ended December 31, 2000,
its directors, executive officers and greater than 10% shareholders complied
with all Section 16(a) filing requirements, with the exception of
Messrs. Gruber, Ahmed, Anderson, Hluchyj, Jones, Mayersohn, Nill, Severino,
Winiarski and Wong whose Forms 3 were all filed one day late; Mr. Severino whose
Form 4 for the month of December 2000 reported one delinquent transaction; and
Mr. Anderson whose Form 4 for the month of January 2001 reported three
delinquent transactions.
 
PROPOSALS AND NOMINATIONS BY SHAREHOLDERS
 
    Shareholders who wish to present proposals for inclusion in Sonus' proxy
materials for the 2002 Annual Meeting of Shareholders may do so by following the
procedures prescribed in Rule 14a-8 under the Securities Exchange Act of 1934
and Sonus' by-laws. To be eligible, shareholder proposals must be received at
Sonus' corporate headquarters in Westford, Massachusetts by the Secretary of
Sonus on or before January 11, 2002.
 
OTHER MATTERS
 
    The Board of Directors knows of no other matters to be submitted at the
meeting. If any other matters properly come before the meeting, it is the
intention of the persons named in the enclosed form of proxy to vote the shares
they represent as the Board of Directors may recommend.
 
    Copies of the our Annual Report on Form 10-K for the fiscal year ended
December 31, 2000 are available without charge to each shareholder, upon written
request to the Investor Relations department at our principal executive offices
at 5 Carlisle Road, Westford, MA 01886.
 
                                       19

<PAGE>
OTHER INFORMATION CONCERNING PROXY SOLICITATION
 
    We will pay the costs of soliciting proxies from shareholders. We have hired
Georgeson Shareholder Communications, Inc. to help us solicit proxies from
brokers, bank nominees and other institutional owners. We expect to pay
Georgeson a fee of $7,500 for its services and will reimburse them for
reasonable out-of-pocket costs estimated to be approximately $2,000. Directors
and officers and regular employees may solicit proxies, either personally or by
telephone, on behalf of Sonus, without additional compensation.
 
                                          By Order of the Board of Directors,
 
                                          Michael G. Hluchyj
                                          Secretary
 
Westford, Massachusetts
April 16, 2001
 
                                       20

<PAGE>

                                                                      APPENDIX A
 
                              SONUS NETWORKS, INC.
                            AUDIT COMMITTEE CHARTER
 
PURPOSE
 
    The primary purpose of the Audit Committee is to assist the Board of
Directors of the Corporation in fulfilling its oversight responsibilities to its
stockholders and to the investment community by reviewing the financial reports
and other financial information provided by the Corporation to its stockholders,
to any governmental body or to the public; the Corporation's systems of internal
control; and the Corporation's auditing, accounting and financial reporting
processes generally. The Committee will maintain free and open communication
among the Audit Committee, the independent auditors and management of the
Corporation. In discharging its oversight role, the Committee is empowered to
investigate any matter brought to its attention with full access to all books,
records, facilities, and personnel of the Corporation and the power to retain
outside counsel or other experts for this purpose.
 
COMPOSITION
 
    The Committee shall be appointed by the Board of Directors of the
Corporation and shall comprise three or more directors, each of whom shall be
independent and free from any relationship that, in the opinion of the Board,
would interfere with the exercise of his or her independent judgment as a member
of the Committee. All members of the Committee shall have a working familiarity
with basic finance and accounting practices, and at least one member of the
Committee shall have accounting or related financial management expertise.
 
MEETINGS
 
    The Committee shall meet at least four times annually. The Committee shall
meet periodically with management and the independent accountants, or in
separate executive sessions, to discuss any matters that the Committee or either
of these groups believes should be discussed privately. The Committee may meet
by telephone and may delegate specific functions to one or more of its members.
 
RESPONSIBILITIES AND DUTIES
 
    To fulfill its purpose, the Committee shall:
 
    REVIEW CHARTER AND FINANCIAL STATEMENTS
 
1.  Review and update this Charter periodically, at least annually, as
    conditions dictate.
 
2.  Review the organization's annual financial statements and any report of
    other financial information submitted to the stockholders, any governmental
    body or the public, including any certification, report, opinion or review
    rendered by the independent accountants. The Committee is not responsible
    for preparing the Corporation's financial statements or auditing those
    financial statements.
 
    INDEPENDENT ACCOUNTANTS
 
4.  Recommend to the Board of Directors the selection of the independent
    accountants, after considering their independence. On an annual basis, the
    Committee should review and discuss with the accountants their written
    statement concerning all significant relationships the accountants have with
    the Corporation to determine whether such relationships could improperly
    affect the accountants independence.
 
5.  Review the performance of the independent accountants and either recommend
    or approve any discharge of the independent accountants when circumstances
    warrant.

<PAGE>
6.  Periodically consult with the independent accountants out of the presence of
    management about internal controls and the fullness and accuracy of the
    organization's financial statements.
 
    INTERNAL CONTROLS
 
7.  Consider and review with the independent accountants and management:
 
    (a) The adequacy of the company's internal controls including computerized
       information system controls and security.
 
    (b) Any related significant findings and recommendations of the independent
       accountants together with management's responses thereto.
 
    FINANCIAL REPORTING PROCESS
 
8.  In consultation with the independent accountants review the adequacy of the
    organization's financial reporting processes, both internal and external.
 
9.  Consider the independent accountants' judgments about the quality and
    appropriateness of the Corporation's accounting principles as applied in its
    financial reporting.
 
10. Consider and approve, if appropriate, major changes to the Corporation's
    auditing and accounting principles and practices as suggested by the
    independent accountants or management.
 
11. Prepare a Committee report to the stockholders.
 
    SYSTEMS AND CONFLICTS
 
12. Establish systems for management and the independent accountants to report
    to the Committee any significant judgments made in management's preparation
    of the financial statements and the appropriateness of such judgments.
 
13. Following the completion of the annual audit, review separately with each of
    management and the independent accountants any significant difficulties
    encountered during the course of the audit, including any restrictions on
    the scope of work or access to required information.
 
14. Review any significant disagreement between management and the independent
    accountants with regard to the preparation of the financial statements.
 
15. Review with the independent accountants and management the extent to which
    changes or improvements in financial or accounting practices, as approved by
    the Committee, have been implemented.
 
                                     * * *
 
This charter has been adopted by resolution of the Board of Directors on
December 15, 2000.
 
                                      A-2

<PAGE>

SONUS NETWORKS, INC.
2001 ANNUAL MEETING TO BE HELD ON MAY, 11, 2001 EST
FOR HOLDERS AS OF 04/11/01

         CUSIP:

                                               PLEASE INDICATE YOUR VOTE BY
                                               PLACING AN "X" IN THE APPROPRIATE
                                               BOX FOR EACH PROPOSAL

1.       ELECTION OF DIRECTORS        1.  {  } FOR ALL NOMINEES
         DIRECTORS RECOMMEND A            {  } WITHHOLD ALL NOMINEES
         VOTE "FOR" ELECTION OF           {  } WITHHOLD AUTHORITY TO VOTE
         THE FOLLOWING NOMINEES:               ANY INDIVIDUAL NOMINEE. WRITE
                                               NAME OF NOMINEE BELOW
         PAUL J. FERRI
         RUBIN GRUBER                          -----------------------------


                                            FOR     AGAINST  ABSTAIN

2.       AMENDMENT TO SONUS' AMENDED  2.   {   }     {   }    {   }

         AND RESTATED CERTIFICATE 
         OF INCORPORATION TO INCREASE
         THE NUMBER OF AUTHORIZED SHARES
         OF COMMON STOCK FROM 300,000,000
         SHARES TO 600,000,000 SHARES
         DIRECTORS RECOMMEND A
         VOTE "FOR" PROPOSAL 2

                                            FOR     AGAINST  ABSTAIN

3.       RATIFICATION OF              3.   {   }     {   }    {   }
         APPOINTMENT OF INDEPENDENT
         ACCOUNTANTS

ENTER YOUR VOTING INSTRUCTIONS AT 1-XXX-XXX-XXXX   PLACE "X" HERE IF YOU PLAN TO
OR WWW.GEORGESON.COM UP UNTIL 11:59 PM             ATTEND AND VOTE YOUR SHARES
EASTERN TIME THE DAY BEFORE THE CUT-OFF            AT THE MEETING
OR MEETING DATE.                                   {    }

<PAGE>

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