Industry Analyst Reports Sonus-Based Networks Carry 3x More Long Distance VoIP Traffic than Any Other Equipment Vendor

CHELMSFORD, MA, March 29, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that leading industry analyst firm, iLocus, confirmed Sonus solutions are the preferred foundation for today's leading next-generation telecommunications networks. Carrying more than 53 billion minutes of packet voice traffic in Q4 2005, Sonus leads both the national and international long distance market with approximately 37% and 28% of the market, respectively, according to a recent report published by iLocus. With more than 35% of the total combined long distance market, Sonus-based networks carried 3x the amount of packet voice minutes than any other equipment provider.

“When we measure the growth in the next-generation telecommunications market and the status of its key players, minutes of use is a valuable metric because it demonstrates what is real and in deployment today,” said Jahangir Raina, Founder and Director at iLocus. “Sonus' ability to scale rapidly in tandem with its customers' changing needs has earned the Company a strong leadership position in the long-distance VoIP market. Sonus has announced relationships with over 50 customers around the world, and the largest next-generation voice networks running live traffic today rely on Sonus as the foundation for their networks.”

Network operators globally are transforming their telecommunications networks to IP, making it the foundation for the delivery of enhanced voice and multi-media services. Voice delivery requires robust levels of scalability, reliability and proven performance. According to the iLocus report, an estimated 206.8 billion minutes of packet voice traffic was carried by service providers worldwide in the fourth quarter of 2005. Of these minutes, 75.3 billion was local call volume, 113.7 billion was national long distance (NLD) call volume, and 17.8 billion was international long distance (ILD) call volume. Sonus' IP Multimedia Subsystem (IMS)-ready solutions were designed to meet the critical levels of quality assurance required for today's next-generation telecommunications networks. Sonus' innovation and technology leadership has resulted in its solutions being selected as the foundation for some of the most complex voice networks in the United States. Sonus is also the recognized preferred provider of next-generation voice solutions in Japan.

“Sonus is focused on helping our customers leverage their investment in our solutions to deliver the cost savings, operating efficiency, and application delivery benefits that are unique to IP-based networks,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “The growth of our customers' networks has demonstrated the scalability, reliability and performance of Sonus' advanced IMS-ready solutions, and as we continue to scale our deployments with our existing providers and embark on new deployments, our commitment to their success remains unwavering.”

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, 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 Chelmsford, 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 the “Risk Factors” section of Sonus' Annual Report on Form 10-K, dated March 14, 2006, filed with the SEC, which identify 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 associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities 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.

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