Industry Leader Delivers Year-Over-Year Quarterly Growth and Increased Profitability

WESTFORD, Mass., May 8, 2008 - Sonus Networks, Inc. (Nasdaq: SONS), a market leader in IP communications infrastructure, today reported financial results for the first quarter ended March 31, 2008.

Revenues for the first quarter of fiscal 2008 were $74.0 million, compared with $97.1 million in the fourth quarter of fiscal 2007 and $71.1 million for the first quarter of fiscal 2007.  Net income on a GAAP basis for the first quarter of 2008 was $0.6 million, or $0.00 per diluted share, compared to GAAP net income of $14.1 million, or $0.05 per diluted share, for the fourth quarter of 2007, and a GAAP net loss of $4.0 million, or $0.02 per share, for the first quarter of 2007.

The Company's results include stock-based compensation and related expenses, stock option review costs, amortization of intangible assets related to the April 2007 purchase of Zynetix, a change in estimate of a loss contingency related to an employment tax audit in connection with the stock option review and an insurance recovery related to the 2004 restatement litigation settlement.  The amount of each item included in our financial information is available in the "Supplemental Information" schedule attached.  On a pre-tax basis, these amounts totaled $7.4 million of expense in the first quarter of 2008, a net gain of $7.5 million in the fourth quarter of 2007 and $13.7 million of expense in the first quarter of 2007.  Excluding these items, non-GAAP net income for the first quarter of 2008 was $5.2 million, or $0.02 per diluted share, compared with $12.0 million, or $0.04 per diluted share for the fourth quarter of 2007 and $4.8 million, or $0.02 per diluted share, for the first quarter of 2007.

The Company had another strong quarter from a cash perspective. In the first quarter of 2008, cash, cash equivalents and investments increased by approximately $15 million, totaling over $407 million at March 31, 2008.  Additionally, the Company continues to have no debt.

"Our first quarter results demonstrate the diversity of our business and a solid global environment for IP communications," said Hassan Ahmed, chairman and CEO of Sonus Networks.  "Fueled by the growth of the IP-services market, Sonus' global business continues to expand, and the demand for our solutions continues to increase. With another period of year-over-year quarterly revenue growth, we're delivering results and executing on our long term strategy.  During the last year, there has been increased adoption of Sonus solutions by incumbent operators and the transformation underway in today's communications networks has expanded from fixed-line to include mobile networks.  Sonus is gaining momentum and is well positioned to execute on our goals."

First Quarter Fiscal 2008 Business Highlights:

In the first quarter of fiscal 2008, Sonus introduced innovative new technology to the market and announced important customer expansion that will fuel growth in 2008 and beyond.

New Products

• In February 2008, Sonus introduced the mobilEdge™ Wireless Access Node. This new solution allows network operators to combine their high-speed data networks with picocell or femtocell technology to maximize the investment they have previously made in their wireless broadband networks.  Further, the mobilEdge solution allows operators to generate increased minutes and improve the average revenue per user with broader wireless access and additional services
• In February 2008, Sonus announced its Centralized Call Routing Database. Sonus' Centralized Call Routing Database leverages the Sonus PSX™ Policy Server, which allows mobile operators to consolidate routing decisions in a central location instead of provisioning each individual mobile switching center. It delivers enhanced network performance and efficiency by providing mobile operators with Transcoder-Free Operation (TrFO). By eliminating the need to convert signals between disparate mobile networks, network operators free additional network capacity
• In March 2008, Sonus announced the latest release of its IP Multimedia Subsystem (IMS) core architecture, including upgrades to its SRX™ Call Session Control Function and HSX™ Home Subscriber Server. With its latest release, Sonus empowers network operators to deliver advanced multimedia communications applications and services on a standards-based platform built to meet the rigorous scalability, reliability and security needs of today's largest network operators

Global Customer Announcements

• In the UK, The Carphone Warehouse Networks announced that over one million phone users in the UK are now live on its next generation network infrastructure which is supported by the Sonus IP-based platform. Sonus technology is supporting the dramatic expansion in The Carphone Warehouse Networks' residential voice business, and the major milestone of more than one million subscribers was achieved in just 27 months. The Carphone Warehouse Networks estimates that by 2010 it will have 3.5 million broadband subscribers for this service.

Industry Leadership

Independent market researchers reported that Sonus increased its market share in the fourth quarter of 2007, extending its leadership position and outpacing the market and its competition.

• Synergy Research Group, a leading independent industry research firm, named Sonus the market share leader in key segments of the IP-voice market in its "4Q07 Service Provider Worldwide VoIP Market Share Report."  Synergy reported that Sonus grew more than twice as fast as the industry average in key segments of the next generation voice solutions industry during Q4 2007 versus Q3, and increased its market share leadership position for 2007 as a whole. In 2007, Sonus outpaced the market, securing #1 market share in the global high density gateway segment.  In the total global VoIP gateway market, Sonus' annual performance of 19% moved the Company from #3 in 2006, to #1 in 2007 "Looking forward, we remain optimistic about our growth opportunities as we continue to expand our presence around the world and move deeper into our core market segments.  Demand continues to be healthy for our solutions and services in each of our core markets and geographic regions and we are continuing our deployments with some of the world's largest operators," concluded Ahmed

About Sonus Networks

Sonus Networks, Inc. is a market leader in IP communications infrastructure for wireline and wireless service providers. With its comprehensive IP Multimedia Subsystem (IMS) solution, Sonus addresses the full range of carrier applications, including residential and business voice services, wireless voice and multimedia, trunking and tandem switching, carrier interconnection and enhanced services. Sonus' voice infrastructure solutions are deployed in service provider networks worldwide. Founded in 1997, Sonus is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com. This release may contain forward-looking statements regarding future events that involve risks and uncertainties. Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results. Readers are referred to Item 1A "Risk Factors" of Sonus' Annual Report on Form 10-K for the period ended December 31, 2007, filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. Risk factors include among others: the impact of material weaknesses in our disclosure controls and procedures and our internal control over financial reporting on our ability to report our financial results timely and accurately; the unpredictability of our quarterly financial results; risks and uncertainties associated with the Company's restatement of its historical stock option granting practices and accounting including regulatory actions or litigation; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities and patent litigation against the Company. Any forward-looking statements represent Sonus' views only as of today and should not be relied upon as representing Sonus' views as of any subsequent date. While Sonus may elect to update forward-looking statements at some point, Sonus specifically disclaims any obligation to do so, except as required by law.

Sonus is a registered trademark of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.