Dell'Oro Group Analysis Shows Sonus Growing Faster than the VoIP Market

CHELMSFORD, Mass., March 07, 2005 - Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that industry research firm Dell'Oro Group found that, in 2004, Sonus increased its market share in core segments of the carrier voice over IP (VoIP) equipment market, outpacing the industry's overall growth.

Market research conducted by Dell'Oro Group for 2004 showed that Sonus grew 117 percent year-over-year in the total carrier IP telephony market, compared with overall market growth of 26 percent. According to the report, Sonus gained more market share than any other vendor in this category, increasing its share from 4.7 percent in 2003 to 8.1 percent in 2004. In the high-density gateway revenue market, Sonus grew 114 percent year-over-year, increasing its market share from 16.6 percent in 2003 to 24.4 percent in 2004 and also increasing its lead over competitors. For 2005, Dell'Oro Group forecasts 32 percent growth for the total carrier IP Telephony market.

"2004 was an important turning point in the adoption of VoIP technologies by major carriers, and Sonus was one of the primary beneficiaries of service providers' commitment to building out VoIP networks," said Steve Edwards, chief marketing officer, Sonus Networks. "Sonus continues to post impressive gains and to make traction in key markets. This market leadership reflects our ongoing work with our customers who are expanding their Sonus-based deployments to carry an increasing amount of VoIP traffic and deliver new services."

The Dell'Oro Group report provides market share estimates developed by Dell'Oro Group.

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/A dated July 28, 2004 and filed with the SEC, and the "Cautionary Statements" section of Sonus' 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' 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.