Sonus Drives Global VoIP Traffic in 2004; Networks Based on Sonus Solutions Now Carry Estimated 10 Billion Minutes of Traffic Monthly.

CHELMSFORD, Mass. -- Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced a significant milestone in the evolution of the worldwide VoIP industry. In the month of December alone, service providers globally reported that they are now carrying an estimated 10 billion minutes of customer traffic per month on their Sonus-based networks, representing a significant increase from the estimated 6 billion minutes per month in December 2003.

"VoIP technology is the first major structural shift in telecommunications infrastructure in the last fifty years. The market has now reached mainstream adoption as carriers worldwide are recognizing the benefits of VoIP architectures," said Mike Hluchyj, founder and chief technology officer, Sonus Networks. "Our announcement today is a major milestone not only for Sonus, but also for the industry at large. Carriers globally are continuing to accelerate their adoption of VoIP technologies, and we are pleased that Sonus continues to be recognized as a leader in such an exciting and important industry."

Recently released worldwide traffic data from Probe Research Group showed that Sonus-based networks continue to carry a significant percentage of the world's VoIP traffic. Sonus' solutions have been proven in some of the most complex and demanding carrier networks in the world today, demonstrating the scalability and reliability of the Sonus platform. As a testament to the strength of Sonus' solutions, carriers and service providers are increasingly transitioning their voice traffic from their legacy circuit-switch networks to their VoIP network.

The rapid growth in worldwide traffic VoIP traffic is reflected in the latest results from the leading market research firms for the equipment market. Infonetics Research recently reported that the carrier VoIP equipment market grew approximately 69 percent in 2004, with Sonus as the global leader in the packet voice gateway revenue for the third quarter of 2004, as well as for the year to date.

"With some of the most discerning carriers in the world as customers, Sonus continues to be a major driver in the adoption of VoIP solutions. Our research shows that carriers are driving increasing amounts of their customer traffic over their next-generation networks. This transition represents a tremendous opportunity for Sonus and the industry overall, as every carrier is expected to move to a VoIP architecture over time," said Kevin Mitchell, Directing Analyst with Infonetics Research.

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 Architecture(TM) (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, Insignus and Sonus Insight are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.