CHELMSFORD, Mass., November 30, 2005 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, announced today that it has been named the leading provider of carrier-class VoIP equipment for the third quarter of 2005 by Infonetics Research and Synergy Research Group, two leading industry research firms. In their recently-issued third quarter 2005 market share reports Infonetics and Synergy both identify Sonus as the industry leader in several key service provider packet telephony market segments, ahead of all traditional TDM vendors.

In Synergy Research Group's “Q3 2005 Worldwide Market Shares” report, the firm states that Sonus increased its market share in the third quarter, garnering approximately 30 percent of the high density gateway market during the period. The report published by Infonetics Research, “Quarterly Worldwide Market Share and Forecasts for 3Q05,” also recognized Sonus' continued momentum, stating that in the third quarter of 2005, Sonus' solutions claimed the leading position for worldwide high density media gateway revenue market share. In addition, both reports noted that the total market for next generation voice solutions increased quarter over quarter.

“Several factors are driving the growth of the service provider VoIP market, including increased migration activities by Public Voice networks, new activity by wireless operators to transition their TDM-based infrastructure to VoIP, the explosive growth of broadband penetration, and increasing consumer and enterprise user demand for enhanced next generation services,” said Jeremy Duke, President & CEO, Synergy Research Group. “Sonus has a keen understanding of each of these market dynamics, and executed effectively in order to earn a number one market share position for the third quarter.”

“Sonus' performance in Q3 is reflective of the company's reputation as a technology leader, innovator, and trusted equipment provider to some of the most dynamic service providers in the industry,” said Jeff Heynen, Directing Analyst, Infonetics Research. “With growing market traction, particularly in Europe and Asia, Sonus continues to be the industry leader in the migration towards sophisticated, robust, all-IP network deployments.”

Sonus' leadership is evidenced by the increasing amount of customer traffic supported by Sonus-powered networks worldwide - reaching a new high of more than 15 billion minutes of voice traffic per month at the end of the third quarter . The Company's IMS-ready solutions have been embraced by traditional telecom service providers, leading wireless carriers, and Internet Service Providers (ISPs). Sonus is now replacing legacy communications systems in leading service provider networks, enabling these operators to experience the benefits of VoIP with demonstrable improvements in cost-efficiency and feature delivery.

“Sonus is proud to have been recognized as the market leader in carrier-class next-generation voice solutions among a field of well established traditional voice communication vendors,” said Steve Edwards, Chief Marketing Officer, Sonus Networks. “We are at the beginning of a fundamental shift in the way voice networks are designed and implemented. Sonus' strong performance reflects the growing demand for VoIP networks that deliver carrier-class reliability and scalability, while providing cost advantages and enhanced features.”

For a copy of the Synergy Research Group report, please contact Heather Wilson at 775.348.6027 or hwilson@srgresearch.com.

For a copy of the Infonetics Research report, please contact Larry Howard at 408.583.3335 or larry@infonetics.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.

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.