Sonus Solutions Selected as Foundation for 360networks' Next-Generation SIP-Based VoIP Platform

CHELMSFORD, Mass., February 27, 2006 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that 360networks Corporation, a large western regional competitive local exchange carrier (CLEC) and leading provider of broadband telecommunication services, has selected the Sonus Networks IMS-ready architecture as the foundation for its SIP-based wholesale VoIP service. 360networks will deploy a complete suite of Sonus solutions, including the GSX9000™ Open Services Switch, the PSX™ Call Routing Server, the SGX™ Signaling Gateway, and the Sonus Insight™ Management System. 360networks' SIP-based wholesale service will enable broadband service providers to enter the VoIP market quickly and cost effectively.

360networks' service will target broadband service providers who need VoIP-to-PSTN call origination and PSTN-to-VoIP termination services. Supported by Sonus' carrier-class IMS-ready architecture, 360networks will provide an a la carte menu of wholesale services that include local telephone numbers, inbound/outbound local calling, toll termination, E911, local number portability, directory listing, operator services, and directory assistance. The service will be available in rate centers throughout the western half of the United States. The service will leverage 360's competitive local exchange status and robust fiber optic network with reach into tier 1, 2, 3, and 4 markets throughout the western U.S.

“Our goal is to deploy a carrier-class quality SIP-based wholesale service to enable broadband service providers to quickly and cost effectively deliver VoIP services to their end-user customers,” said Rick Coma, Sr. Vice President of 360Networks. “Our wholesale service will be a critical component for our customers as they look to deliver wireline replacement services, and by selecting Sonus as the foundation for our network we have the ability to deliver the quality our customers expect.”

“Sonus is a market leader in next generation VoIP solutions. We're excited that 360networks has chosen to leverage our extensive expertise in this area as they aggressively enter the voice market.” said Hassan Ahmed, chairman and CEO, Sonus Networks.

According to iLocus Research, Sonus is the number one market share leader in long distance IP voice solutions. Sonus-based networks carry approximately 40% of the world's IP-based long distance traffic.

“Sonus has played a key role in stimulating the growth of the VoIP market by providing carrier-class infrastructure solutions that are relied upon by some of the world's largest service providers,” said Jahangir Raina, Founder and Research director with iLocus Research. “To date, less than 15% of the world's long distance traffic is carried over IP technologies, which means there is still a significant opportunity for a company like Sonus to continue to grow its business.”

360networks is scheduled to deploy its SIP-based wholesale service in rate centers throughout the western half of the US. The service will be commercially available in the second half of 2006.

About 360networks

360networks offers telecommunications services and network infrastructure on the largest regional network in the Western United States spanning 16,000 miles and connecting thirty-nine Tier 1, 2, and 3 metro markets. The Company's products include wavelengths, OC-n, IP and VoIP services. 360networks markets to telecom carriers, data service providers, enterprises and emerging VoIP service providers. Among the company's customer base are many of the leading telecom service providers in North America. Visit http://www.360.net.

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, Inc. Sonus GSX9000 Open Services Switch, PSX Call Routing Server, SGX Signaling Gateway, and the Sonus Insight Management System are trademarks of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.