Sonus Extends Market Leadership

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Sonus Ranks # 1 in Several Segments of the Carrier Packet Voice Market for 2004

CHELMSFORD, Mass., March 30, 2005 - Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, announced today that industry research firms In-Stat and Synergy Research Group reported that Sonus increased its market share in several segments of the carrier packet voice market for 2004

According to In-Stat, Sonus achieved year-over-year growth of 73 percent in both the total voice gateway and high-density gateway categories. In 2004, Sonus continued to gain share, expanding its market position from approximately 34 to 40 percent in the high-density gateway market. The findings from In-Stat also show that Sonus increased its market share more than any other vendor.

Market research conducted by Synergy Research Group for 2004 names Sonus as the leader in high density gateway revenue with approximately 38 percent of market share. Additionally, Sonus grew faster than both the service provider VoIP market and total media gateway market. In service provider VoIP revenue, Sonus demonstrated an impressive 82 percent year-over-year growth in 2004, versus total market growth of 45 percent. Similarly, in total media gateway revenue, Sonus displayed 68 percent year-over-year growth in 2004, while the market grew 37 percent during that same period of time.

“The market for VoIP equipment grew steadily during 2004, and Sonus continues to play an important role in the driving the adoption of VoIP technologies by carriers around the world,” said Jeremy Duke, Founder, President and CEO at Synergy Research Group. “In 2004, Sonus expanded its worldwide footprint, with the announcement of new partnerships and customer deployments. We expect to see Sonus continue to be a major force in the VoIP market in 2005.”

"2004 was a great year for Sonus, both in terms of expanding our deployments within existing customers and being selected by new carriers," said Steve Edwards, chief marketing officer, Sonus Networks. "We are excited to see the momentum in the market, and are pleased that leading research firms such as In-Stat and Synergy Research Group recognize the critical role Sonus is playing in the development of today's next generation networks."

The In-Stat and Synergy Research Group research reports provide market share estimates developed by In-Stat and Synergy Research Group respectively.

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 Open Services ArchitectureTM (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking and tandem switching, residential and business access, network border switching and enhanced services. Sonus' voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide. Sonus, founded in 1997, 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 15, 2005, and filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. In addition, 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.

Sonus is a registered trademark of Sonus Networks. Open Services Architecture, GSX9000 and Insignus are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.