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VoIP Market Leader Leases New Facility in Chelmsford, Massachusetts

WESTFORD, Mass., December 22, 2003 – Sonus Networks (Nasdaq: SONS), a leading provider of carrier packet voice infrastructure solutions, today announced that it will relocate its corporate headquarters to Chelmsford, Massachusetts. Sonus has signed a sublease under which it will occupy more than 130,000 square feet of space at 250 Apollo Drive in Chelmsford. The company is expected to complete the move of its operations to the new facility by the end of the first quarter 2004.

"We had several goals in mind when selecting the location of our new corporate headquarters," said Hassan Ahmed, president and CEO, Sonus Networks. "It was very important that we stay in the Route 495 area, the heart of Massachusetts" telecommunications corridor, for our employees and for our customers. Additionally, we required state-of-the art engineering, professional services and customer support facilities. We are extremely pleased to have found a new home that meets our criteria, and at the same time offers financial advantages over our current facilities. We are looking forward to making the move to Chelmsford."

Sonus employs nearly 400 personnel worldwide, with more than 260 employees based in Massachusetts. Sonus' new facilities in Chelmsford will satisfy the company's future space requirements as Sonus expands its Massachusetts employee base over the coming years.

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure solutions for wireline and wireless service providers. With its Open Services Architecture (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 the "Cautionary Statements" section of Sonus' Quarterly Report on Form 10-Q, dated November 10, 2003 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 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. 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 is a trademark of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.