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Respected Industry Research Firms Name Sonus #1 in Q3 Market Share Reports

WESTFORD, Mass., November 20, 2002 – Sonus Networks (Nasdaq: SONS) today announced that it has again been named the leading provider of carrier-class packet voice equipment. Market analysis firms In-Stat/MDR, Infonetics Research and Synergy Research Group recently issued third quarter 2002 market share reports identifying Sonus as the industry leader in several key service provider packet telephony market segments.

"It is extremely gratifying to be named the leader in delivering next-generation packet voice solutions to service providers, a position we have held for nine consecutive quarters," said Michael O'Hara, vice president of marketing, Sonus Networks. "This continued market leadership reflects our ongoing work with our customers, who are carrying increasing amounts of voice traffic and delivering new services on their Sonus-based networks every day. That is a true measure of market leadership."

In its third quarter market share analysis, In-Stat/MDR named Sonus the leader in several categories, including purpose-built carrier voice over IP (VoIP) gateway port shipments and revenues and high-density VoIP gateway port shipments and revenues.

"Despite the challenging conditions in the telecommunications environment, Sonus continues to add new customers and expand deployments with existing customers," said Norm Bogen, director, WAN Infrastructure and Services at In-Stat/MDR. "The combination of these critical success factors reinforces Sonus' position as a leading player in the carrier voice over packet (VoP) market."

Infonetics Research again ranked Sonus the number one provider of convergence switches, in both port shipments and revenues. Their 3Q02 report, Next Gen Voice Products, named Sonus the industry leader in revenues and DS0 shipments for the VoP and combined VoP/ICD applications of convergence switches.

"We remain positive on the market outlook for next-generation packet voice and the benefits this technology delivers to service providers," said Kevin Mitchell, directing analyst, Service Provider Networks, Infonetics Research. "Our most recent findings show that Sonus maintained the number one market share in the convergence switch market segment. Their leadership position is more pronounced in the VoP application, where they have 47% of third quarter revenue."

Last week, Synergy Research Group issued its Q3 2002 report on worldwide VoIP equipment market share. In the Synergy report, Sonus was the top provider of high-density VoIP gateways in both revenues and port shipments.

"In our third quarter market share analysis, Sonus continues to hold a commanding lead in providing high-density carrier class VoIP gateways to the industry," said Jeremy Duke, founder and principal analyst, Synergy Research Group. "Even after more than two years, Sonus continues to garner the lion's share of this next-gen packet voice market."

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture^TM (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services.Sonus' award-winning 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 Westford, Massachusetts.  Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus 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 Sonus' Quarterly Report on Form 10-Q, dated November 13, 2002 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.These risk factors include, among others, the adverse effect of recent developments in the telecommunications industry, the weakened financial position of many service providers, Sonus' ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change and manufacturing and sourcing risks.

Open Services Architecture is a trademark of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.