Sonus-Based Networks Carry over 17 Billion Minutes of VoIP Traffic Per Month at Year-end 2005

CHELMSFORD, Mass., January 17, 2006 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, announced today that the amount of voice traffic being carried over Sonus' industry-leading solutions exceeded 17 billion minutes per month at the end of 2005, a 70 percent increase compared to December 2004. Network operators around the world are supporting increasing amounts of customer traffic over Sonus IMS-based architectures to deliver innovative new applications and features to consumers, achieve superior operating efficiencies, and prepare their telecommunications networks for a seamless migration to full IMS-compliance.

“Over the past year, we've expanded our business with network operators across all segments of the market. Traditional telecom providers, Internet Service Providers, and wireless operators have embraced Sonus technology and accelerated their migration towards an all IP-based network architecture,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “We're proud of the success we've witnessed in some of today's most advanced telecommunications networks, and we anticipate the amount of voice traffic supported by Sonus-based networks to continue to increase at a rapid pace as the world's communications networks continue the transition to VoIP.”

“Sonus' voice over IP infrastructure technology has helped us provide robust, secure Internet voice services that meet our customers' communications needs,” said Steve Howe, vice president of voice for EarthLink. “Sonus' technology allows for enriched communication applications and the rapid integration of multiple services, such as our Line Powered Voice and other premium voice products.”

“Our Sonus-based network has enabled us to introduce significant value-add services to our customers through the delivery of enhanced next-generation applications,” said Randy Nicklas, vice president of network engineering at XO Communications. “Further, the reliability and scalability of our Sonus-based network has allowed us to grow our network and hit new milestones as the demand for our broad suite of commercial and wholesale VoIP solutions continues to increase.”

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 comprehensive IP Multimedia Subsystem (IMS) solution, Sonus addresses the full range of carrier applications, including residential and business voice services, wireless voice and multimedia, trunking and tandem switching, carrier interconnection and enhanced services. Sonus' voice infrastructure solutions are deployed in service provider networks worldwide. Founded in 1997, Sonus 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, dated March 15, 2005, and the “Cautionary Statements” section of Sonus' Quarterly Report on Form 10-Q, dated November 8, 2005, both filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. Risk factors include among others: the impact of material weaknesses in our disclosure controls and procedures and our internal control over financial reporting on our ability to report our financial results timely and accurately; the unpredictability of our quarterly financial results; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities litigation against the company. 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. All other company and product names may be trademarks of the respective companies with which they are associated.