Central European Telecommunications Provider Selects Sonus Networks For Voice Over Broadband Network Deployment

Strategic Partner NK Networks & Services Delivers Complete Sonus Solution to eTel for Next Generation Voice Network

CHELMSFORD, Mass., December 12, 2006 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that eTel, an Internet Service Provider (ISP) and fixed telephony service provider in Central Europe, has selected Sonus' Voice over Broadband (VoBB) network infrastructure as the foundation for its next generation voice network. The Sonus solution will be delivered through the Company's strategic partner, NK Networks & Services, an independent IT-network and telecommunications systems integrator, which extends Sonus' presence in the German, Austrian and Swiss telecommunications markets. eTel will leverage the Sonus-based platform to deliver a broad suite of consumer and business voice services.

"eTel is a great example of the momentum in the European market. Network operators throughout the region are actively embracing complete, end-to-end next generation voice networks to deliver competitive offerings with rich, multimedia services,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “We're also pleased to announce that our strategic relationship with NK Networks & Services is effectively increasing Sonus' traction throughout Central Europe.”

eTel is deploying a complete end-to-end suite of Sonus' IP Multimedia Subsystem (IMS)-ready solutions for the VoBB market, including both the GSX9000™ and GSX4000™ Open Services Switch, the PSX™ Call Routing Server, the ASX™ Access Server, and the Sonus Insight™ Management System for advanced centralized OSS and billing support. eTel selected the Sonus platform for its field-proven scalability and sophisticated centralized management system.

“eTel has earned a position as one of Europe's leading alternative communications providers by offering a robust portfolio of voice and data services at competitive prices,” said Ilias Liakopoulos, chief technology officer, eTel. “By leveraging our relationship with NK Networks & Services to deploy a Sonus-based Voice over Broadband network, we're able to further enhance our ability to deliver compelling services to our customers.”

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 Item 1A “Risk Factors” of Sonus' Quarterly Report on Form 10-Q dated May 8, 2006, filed with the SEC, which identifies 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 and uncertainties associated with the Company's announced review of its historical stock option grants and accounting, including any potential impact on the Company's financial statements or results, any tax liabilities or penalties, the Company's inability to timely report with the Securities and Exchange Commission, the Company's potential inability to meet NASDAQ requirements for continued listing, potential investigations, regulatory actions or litigation arising out of the review or any restatement; 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.

The product information in this press release is for informational purposes only and is subject to change at Sonus' sole discretion without notice. Sonus has no obligation or commitment to develop or deliver any future release, upgrade, feature, enhancement or function described in this release. The information is provided “AS IS,” with all faults, and without any warranties whatsoever, express or implied, including, but not limited to, warranties of merchantability, performance, or fitness for a particular purpose.

Sonus is a registered trademark of Sonus Networks, Inc. IMS Forum & IMS PlugFest are trademarks of the IMS Forum, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.

Sonus is a registered trademark of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.