Dell'Oro Group, Infonetics Research, In-Stat/MDR and Synergy Research Group Name Sonus Leader in Several Carrier Packet Voice Segments

CHELMSFORD, Mass., December 14, 2004 - Sonus Networks (Nasdaq: SONS) today announced that industry research firms Dell'Oro Group, Infonetics Research, In-Stat/MDR and Synergy Research Group have all named Sonus as the market share leader in several segments of the carrier voice over IP (VoIP) equipment market, according to quarterly market share reports for Q3 2004. Sonus' strong performance was driven by key customer relationships with tier one carriers across the globe.

Market research conducted by Dell'Oro Group for Q3 2004 named Sonus the leader in high-density IP telephony carrier gateway ports, while recent market analysis by Infonetics Research revealed that Sonus remains the overall market leader in Packet Voice Gateway revenue and expanded its lead in the quarter. In addition, both In-Stat/MDR and Synergy Research Group reported that Sonus leads the industry in high-density gateway VoIP revenue and shipments of high-density gateway VoIP ports.

“From the beginning, Sonus has been an innovator and a leader in the VoIP industry. Some of the most recognizable brands in the telecom industry have built successful next-generation networks based on Sonus, including AT&T, NTT Communications, SBB, and T Systems. We are pleased that these research firms continue to reaffirm our standing in this highly competitive market,” said Steve Edwards, chief marketing officer and general manager, EMEA, Sonus Networks. “2004 has been an important year for Sonus and the industry overall, as carriers' adoption of VoIP solutions continues to accelerate and Sonus builds on its momentum in the market.”

In Q3, Sonus Networks reported that while both the access and wireless markets represent exciting new opportunities for growth, the majority of the company's revenue is a result of Sonus' leadership position in the trunking market.

“With both Global Crossing and Qwest Communications on its roster of distinguished customers, Sonus has already had a dramatic impact on the trunking segment of the VoIP market. Our research shows that among carrier VoIP adopters, while the average percentage of packet traffic is still in the single digits, there is tremendous growth ahead for the packet voice equipment market, especially in areas that Sonus is now pursuing, such as access and wireless,” said Kevin Mitchell, Directing Analyst with Infonetics Research.

“Sonus is one of the most steadfastly high-performing companies in the VoIP market today. They continue to innovate on the product side, delivering top-of-the-line solutions to their existing customers and winning favor with the carriers integrating VoIP infrastructure into their networks,” said Norm Bogen, director, Networking, In-Stat/MDR. “Competition in the market is very intense, and the fact that Sonus is consistently ranked at the top of the market segment it serves speaks volumes about the quality of their solutions.”

“This quarter, industry-wide sales of service provider VoIP equipment increased 48.8% sequentially and 149.5% year over year. With more circuit networks migrating to VoIP, the introduction of consumer VoIP services, and wireless operators incorporating packet equipment into their overall strategies, the VoIP market is growing at a rapid pace. Equipment providers like Sonus are leading the way,” said Jeremy Duke, President and CEO, Synergy Research Group.

The Dell'Oro Group, Infonetics, In-Stat/MDR and Synergy reports provide market share estimates developed by Dell'Oro Group, Infonetics, In-Stat/MDR and Synergy 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 Architectureä (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's 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's Annual Report on Form 10-K/A dated July 28, 2004 and filed with the SEC, and the “Cautionary Statements” section of Sonus's Quarterly Report on Form 10-Q, dated November 9, 2004 and filed with the SEC, which identify 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's views only as of today and should not be relied upon as representing Sonus's 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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