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In-Stat/MDR, Infonetics Research and Synergy Research Group Name Sonus #1 in Quarterly Market Share Reports

WESTFORD, Mass., August 20, 2002 – Sonus Networks (Nasdaq: SONS) today announced that for the eighth consecutive quarter, the company has been ranked the leading provider of carrier-class packet voice equipment. Respected industry research firms In-Stat/MDR, Infonetics Research and Synergy Research Group issued Q2 2002 market share reports naming Sonus the industry leader in key packet voice market segments.

"In today's challenging telecommunications environment, carriers are focusing on those projects that can enhance their revenue streams and profitability, and packet voice is one of those opportunities," said Michael O'Hara, vice president, marketing, Sonus Networks. "As highlighted in the market analysis from In-Stat/MDR, Infonetics and Synergy, carriers continue to invest in the transition from circuit to packet voice architectures, and we are pleased to be the market player leading this transition."

In-Stat/MDR released its findings for the second quarter, naming Sonus the leader in several categories, including purpose-built carrier voice over IP (VoIP) gateway port shipments and revenues; high density VoIP gateway port shipments and revenues; and total VoIP gateway ports shipped in all product segments.

"Sonus continues to distance itself from the competition, and in fact, gained market share in the second quarter," said Norm Bogen, director, WAN Infrastructure & Services at In-Stat/MDR. "Leading the market for eight quarters straight, Sonus has established itself as the premier provider of carrier VoIP solutions."

Infonetics Research recently issued its Q2 market share results and forecast, in which Sonus led the market in providing convergence switches, in both port shipments and revenues. Additionally, the Infonetics report named Sonus the industry leader in revenues and DS0 shipments for the VoP applications of convergence switches.

"Packet voice represents the foundation for carriers' future service offerings, enabling the profitable bundling of voice and data services," said Kevin Mitchell, directing analyst, Service Provider Networks, Infonetics Research. "In this critical technology segment, Sonus continues to stand out as the dominant provider of next-gen voice/data switches."

Synergy Research Group ranked Sonus the number one provider for seven segments in its second quarter report on worldwide VoIP equipment market share. According to the Synergy market share analysis, Sonus maintained its lead position in overall service provider VoIP infrastructure port shipments and revenues; service provider VoIP gateway revenues and port shipments (all densities); service provider softswitch revenues; and high-density VoIP gateway revenues and port shipments.

"Sonus continues to set the pace for the carrier packet voice market, having been ranked the industry leader for the past two years," said Jeremy Duke, founder and principal analyst, Synergy Research Group. "In the second quarter, Sonus continued to expand its customer base, further deployments with existing customers and deliver new solutions to the market, all of which fortify Sonus' strategic position as a leading driver in the transition of voice technology from circuit to packet."

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services ArchitectureTM (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 August 14, 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 emerging 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.