Sonus Named Market Share Leader by Independent Industry Research Firm

Infonetics Ranks Sonus #1 in Media Gateway and Packet Voice Gateway Markets

CHELMSFORD, Mass., March 09, 2005 -Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that Infonetics Research has named Sonus the leader in the total media gateway market and total packet voice gateway market for 2004. According to Infonetics, the company gained more share in 2004 than all of its major competitors.

"In a year where VoIP moved from mild adoption to one of the hottest technologies in telecom, Sonus made impressive strides in 2004, moving from number four in total voice gateway market share to the number one position without losing focus on its traditional strongholds, such as the packet voice gateway category, where the company maintained its leadership position for the second year in a row," said Kevin Mitchell, directing analyst at Infonetics Research.

In the total media gateway market, Infonetics Research named Sonus the market share leader with 16.3 percent market share, up from 10.8 percent in 2003. With a 79 percent increase in revenue, Sonus outpaced the market by a significant margin, and surpassed previous frontrunners. In the packet voice gateway market, Sonus maintained its number one market position in 2004 with 33.3 percent of market share, outselling its closest competitor by more than 2 to 1.

"The VoIP market is expanding rapidly. Sonus is uniquely positioned in the industry as the company has been focused from inception on developing the carrier-grade VoIP networks," said Steve Edwards, chief marketing officer, Sonus Networks. "Our continued leadership across market segments and the strength of our relationships with marquis customers, demonstrates the confidence that our customers and the industry as a whole has in our solutions."

The Infonetics Research report estimates Sonus' fourth quarter results based on their own market estimates developed by Infonetics.

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.