Synergy Research Group Names Sonus Market Share Leader in Key Segments of US and Japanese Next Generation Voice Market

CHELMSFORD, Mass., June 14, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that Synergy Research Group, a leading independent industry analysis firm, has named Sonus Networks the market share leader worldwide as well as in both the United States and Japan. Powered by Sonus' industry leading IP Multimedia Subsystem (IMS)-ready solutions, network operators throughout the United States and Japan have demonstrated their ability to scale and offer communication services that typically surpass the quality and features provided by traditional voice offerings. At the same time, new IP-based infrastructure solutions are improving service providers' operating efficiencies and helping to increase average revenue per user.

“As the rapidly increasing volume of IP-based voice traffic supported by Sonus solutions continues to achieve unprecedented levels and now totals almost 20 billion minutes per month, Sonus is proud of the proven scalability of its products and to be driving the industry's evolution,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “From day one, Sonus has strategically aligned its resources to map against areas of the market we forecasted would be the first to embrace IP-based solutions. Geographically, we focused on establishing early footholds in the North American and Japanese markets, a decision that has proved in line with the overall market development and is highlighted by the recent Synergy Research Group report.”

In its report entitled, “Q1 2006 Service Provider VoIP U.S. Market Shares,” Synergy Research Group reported that Sonus increased its position in the U.S. high density gateway market to 36.2% of the overall market. Synergy also reported that in Japan, with 45.9% of the total service provider VoIP infrastructure market, Sonus holds a dominant lead, more than 6x its nearest competitor. In the VoIP high density gateway category specifically, Sonus leads the industry with nearly 87% of the total market.

“The market has reached an important stage where network operators globally no longer question the evolution to IP-based communications networks. Nearly every operator in the United States and Japan has initiated plans to migrate to IP voice, and many have chosen Sonus,” said Jeremy Duke, president and CEO, Synergy Research Group. “Quarter after quarter, Sonus Networks proves to be a leading enabler in the migration to next generation voice networks, adding new customers and helping its existing customer base grow their networks. In Q1 2006, Sonus demonstrated its ability to establish a leading presence in those markets that are most aggressive in their migration to next generation IP-based voice solutions.”

In addition to leadership positions in North America and Japan, Sonus was also named the Q1 worldwide market share leader for high density media gateways by Synergy Research Group. See related release, “Sonus Networks Ranked #1 In Worldwide Carrier Packet Voice Market,” issued May 31, 2006.

“As we look ahead, we will continue to work towards extending our position in these key regions, while at the same time looking ahead to the next phase of the market's evolution, which we anticipate will occur most aggressively among the world's wireless service providers and innovative carriers throughout Europe,” concluded Ahmed.

For a copy of any of the Synergy Research Group reports referenced in this release, please contact Heather M. Wilson, Synergy Research Group, Inc., hwilson@srgresearch.com.

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 and Quarterly Report on Form 10-Q, dated May 8, 2006, both 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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