Industry Leader Reports Record Fourth Quarter and Annual Revenue

WESTFORD, Mass., February 28, 2007 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of serviceprovider Voice over IP (VoIP) infrastructure solutions, today reportedits financial results for the fourth quarter and fiscal year endedDecember 31, 2006.

Revenuesfor the fourth quarter of fiscal 2006 were $79 million compared to $75million in the third quarter of fiscal 2006. Revenues for the full yearfiscal 2006 were $279 million. Cash, cash equivalents and investmentsincreased by $47 million during 2006, to $361 million.

“2006 was agreat year for Sonus. We set new records for revenue, profitability,order activity, cash flow from operations and, perhaps most importantly,consumer and business traffic on our customers' networks. These resultsreflect the increasing momentum for our solutions as the industry movesaggressively to IP,” said Hassan Ahmed, chairman and CEO, SonusNetworks. “Our growing portfolio of products seamlessly brings togethervoice, media and data-rich services empowering today's consumers toaccess real-time personalized services and to always remain connected.It is this vision for the future of communications that is enabling usto make steady progress in boosting our financial performance andcreating value for our shareholders.”

Non-GAAP Financial Metrics Highlights:
The Company is not providing detailed GAAP or non-GAAP financial resultsfor the quarter or full year at this time because the Company has notyet completed its previously announced restatement of certain historicalconsolidated financial statements resulting from its voluntary reviewof the processes by which it has historically granted and accounted foremployee stock options. The Company had previously determined that itwill restate certain historical financial statements to record theadditional stock-based compensation expense, related tax impacts and anyother unrecorded adjustments previously determined to be immaterial.The preliminary, non-GAAP financial metrics provided in this release donot include associated stock-based compensation expense or any impactthat may result from the stock option review and related restatement.

• Fourth quarter gross marginsdeclined modestly from our performance in Q3, but were at the high-endof our target operating model range of 58 - 62%;
• Fourth quarter operatingexpenses increased moderately from Q3 as a percentage of revenue withthe primary increase relating to the voluntary stock option review;
• Fourth quarter net income increased meaningfully over Q4 2005, even before recognizing a significant income tax benefit in Q406;
• Annual gross margins increased modestly as a percentage of revenue from our performance in 2005;
• Annual operating expenses decreased moderately as a percentage of revenue compared to 2005;
• Annual net income increased meaningfully from 2005;
• Deferred revenue as of December 31, 2006 increased to $94 million;
• Finally, cash and cashequivalents, marketable securities and long-term investments as ofDecember 31, 2006 were a record $361 million.

TheCompany also announced that as a result of its increased profitabilityin 2006 and forecasted sustained profitability, it will reverse aportion of the reserve against its deferred tax assets in accordancewith Financial Accounting Standard 109 “Accounting for Income Taxes”(FAS 109) and will record a significant income tax benefit in the fourthquarter of 2006.

Update on Stock-Based Compensation Review
As previously reported, the Company has completed its internal stockoption review and continues to work diligently to complete its analysisof the revised accounting and to file its periodic reports with theSecurities and Exchange Commission (SEC). The Company intends to file aForm 12b-25 with the SEC stating that it will be unable to file its Form10-K for the year ended December 31, 2006 until this process has beencompleted.

TheCompany voluntarily notified the SEC of its internal stock option reviewin August 2006 and expects to receive from the SEC a notice of formalorder of investigation. Sonus has been fully cooperating with the SECand will continue to do so. The Company's Audit Committee completed itsinvestigation of the Company's stock option practices and accounting,which found no improper conduct or violation of Company policies by anymember of the Company's current management.

Fourth Quarter 2006 Summary
In the fourth quarter of 2006, Sonus Networks continued to build itsmarket presence around the globe. In Europe, Sonus announced that eTel,an Internet Service Provider (ISP) and fixed telephony service providerin Central Europe, selected Sonus' Voice over Broadband (VoBB) networkinfrastructure as the foundation for its next generation voice network.The Sonus solution will be delivered through NK Networks & Services,one of the independent IT-network and telecommunications systemsintegrators that Sonus has partnered with to augment its market presenceand direct sales activities. In North America and Asia-Pacific, Sonus'position as the preferred partner by leading network operators wasconfirmed by independent market research groups, Infonetics and SynergyResearch Group, which reported that Sonus holds market share leadershippositions in key segments of the next generation voice market.

In thefourth quarter, Sonus continued its pace of industry-leading innovationby delivering new features that advance IP-voice communications. Sonusdeveloped a suite of IP-based new emergency voice calling features toserve National Security/Emergency Preparedness (NS/EP) needs as outlinedby the National Communications System (NCS), whose Executive Agent isthe Department of Homeland Security. The emergency calling features aredesigned to ensure that NS/EP communications are given priority forcompletion during periods of network congestion, such as during crisesor emergencies. Sonus was selected to develop these features based onthe Company's proven ability to deliver carrier-class, SessionInitiation Protocol (SIP)-based solutions.

Sonus alsoreceived “acceptance status” from the Technical Standards Committee “A”(Telecommunications) of the Rural Utilities Service/Rural DevelopmentUtilities Program (RUS/RDUP), a division of the United States Departmentof Agriculture, for key elements of Sonus' industry leading IMS-readyarchitecture. RUS/RDUP acceptance enhances Sonus' ability to addressmarket opportunities with rural telecommunications providers throughoutthe United States.

Also inthe fourth quarter, Sonus drove industry efforts to promoteinteroperability. The Company participated in the inaugural IMSPlugfest, sponsored by the IMS Forum and hosted at the University of NewHampshire Interoperability Lab (UNH IOL). Sonus Networks successfullyparticipated in all of the Plugfest's rigorous tests, which validatedthe interoperability capabilities of Sonus' IMS-ready solutions.

Beyond theCompany's participation in industry-wide organizations, like the IMSForum and the Plugfest events, the Company continued to expand networkoperator access to IMS-ready applications and services, and announcedthat Soleo Communications was the first member to join Sonus' recentlylaunched Interoperability Certification Program, part of Sonus' OpenServices Partner Alliance (OSPA). Sonus also expanded its partnershipwith Cantata Technology by integrating the Cantata SnowShore® IP MediaServer™ with Sonus' IMS-ready architecture to perform the Media ResourceFunction (MRF) and facilitate the seamless delivery ofsubscriber-focused services and applications.

Sonus'position as the preferred partner of leading network operators and theCompany's continued technological innovation were also substantiated byindependent market research groups, Infonetics and Synergy ResearchGroup, which reported that Sonus holds market share leadership positionsin key segments of the IMS market worldwide, as well as in targetgeographies North America and Japan.

“Given thesustainable macro trends in play throughout the industry and our entirecompany's commitment to our customers, Sonus has strong growthprospects for the future. Over the past year, Sonus successfullyoutpaced the market's growth by anticipating our customers' needs anddelivering the field-proven, industry-solutions required to addressthem. As we look ahead at 2007 and beyond, Sonus will continue toexecute its strategy for leading the market through proactive innovationand superior customer service,” concluded Ahmed.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP)infrastructure solutions for wireline and wireless service providers.With its comprehensive IP Multimedia Subsystem (IMS) solution, Sonusaddresses the full range of carrier applications, including residentialand business voice services, wireless voice and multimedia, trunking andtandem switching, carrier interconnection and enhanced services. Sonus'voice infrastructure solutions are deployed in service providernetworks worldwide. Founded in 1997, Sonus is headquartered in Westford,Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

Thisrelease may contain forward-looking statements regarding future eventsthat involve risks and uncertainties. Readers are cautioned that theseforward-looking statements are only predictions and may differmaterially from actual future events or results. Readers are referred toItem 1A “Risk Factors” of Sonus' Quarterly Report on Form 10-Q datedMay 8, 2006, filed with the SEC, which identifies important risk factorsthat could cause actual results to differ from those contained in theforward-looking statements. Risk factors include among others: theimpact of material weaknesses in our disclosure controls and proceduresand our internal control over financial reporting on our ability toreport our financial results timely and accurately; the unpredictabilityof our quarterly financial results; risks and uncertainties associatedwith the Company's announced review of its historical stock optiongrants and accounting, including the impact on the Company's financialstatements or results, any tax liabilities or penalties, the Company'sinability to timely report with the Securities and Exchange Commission,the Company's potential inability to meet NASDAQ requirements forcontinued listing, potential investigations, regulatory actions orlitigation arising out of the review or any restatement; risksassociated with our international expansion and growth; consolidation inthe telecommunications industry; and potential costs resulting frompending securities litigation against the company. Any forward-lookingstatements represent Sonus' views only as of today and should not berelied upon as representing Sonus' views as of any subsequent date.While Sonus may elect to update forward-looking statements at somepoint, Sonus specifically disclaims any obligation to do so.

Theproduct information in this press release is for informational purposesonly and is subject to change at Sonus' sole discretion without notice.Sonus has no obligation or commitment to develop or deliver any productor future release, upgrade, feature, enhancement or function describedin this release. The information is provided “AS IS,” with all faults,and without any warranties whatsoever, express or implied, including,but not limited to, warranties of merchantability, performance, orfitness for a particular purpose.

Sonusis a registered trademark of Sonus Networks, Inc. All other company andproduct names may be trademarks of the respective companies with whichthey are associated.