Belgacom ICS Selects Sonus Networks for Next-Generation Network Transformation

Carrier Migrates Network to IP Core to Support Business Expansion; Expands Traditional TDM Capacity and Captures Transition to IP Peering

WESTFORD, Mass., and Staines, UK, December 10, 2008 – Sonus Networks, Inc. (Nasdaq: SONS), a market leader in IP communications infrastructure, today announced that it has been selected by Belgacom International Carrier Services (ICS), the ninth largest wholesale voice carrier, to transform its network with next generation IP technology. The IP-based network will enable greater capacity and efficiency through centralized routing, multi-media gateways and secure session control.

Sonus will deliver a next-generation network (NGN) to support Belgacom ICS' strategy for growth throughout Europe, Africa and Asia over the next ten years. The network will offer greater capacity, scalability and availability for its expanding portfolio of wireless and wireline customers, while maintaining the secure, robust and fully redundant service their customers demand. The NGN migration, to be completed by the end of 2009, will enable seamless migration to a SIP core while assuring inter-working with the legacy ISUP connections; supporting the multitude of international standards currently in use by Belgacom ICS.

"The IP-based network delivered by Sonus will expand our capacity, open new opportunities for IP peering and reduce operational expense," commented Johan Wouters, vice president Service Delivery & Engineering at Belgacom ICS. "We have a diverse group of wireless and wired operators worldwide and chose the Sonus next-generation infrastructure to efficiently connect to all of our customers; some using the newest SIP core and others still with a legacy network. Sonus offers the best technology and vision to support our objectives to grow our business faster and more cost effectively."

Sonus is deploying a next generation network that will centrally manage policy and routing on the Belgacom ICS network regardless of the traffic type. The same implementation will concurrently support Belgacom ICS legacy TDM traffic and next generation IP traffic. As their wholesale customers move to all IP environments, the Belgacom ICS investments in Sonus gateway hardware will transition to IP session border security and media transcoding.

"Wireless and wireline carriers recognize the value of wholesale partners that support next generation IP peering. Belgacom ICS is well positioned to capture this market transition," commented Mohammed Shanableh, vice president, worldwide sales for Sonus Networks. "By moving to an all IP core for voice services, Belgacom ICS can increase their return on investment as compared to maintaining a traditional network and more quickly get enhanced services into the market; staying ahead of the competition."

The network will be made up of the GSX9000^TM Open Services Switch, PSX^TM Call Routing Server, SGX^TM Signaling Gateway, the Sonus Insight^TM Management System, as well as Sonus' Network Border Switch (NBS) for enhanced border security and advanced IP peering capabilities.

About Belgacom ICS

Belgacom International Carrier Services S.A./NV (Belgacom ICS) is a leading global carrier of voice, data and value added services to 500 wireless, wireline and service providers through sales offices in Brussels, Bern, Dubai, Singapore and New York. Belgacom ICS is at the forefront of the international communications industry, acting as a catalyst for growth, both in terms of traffic and reach. The company aims to enable global interworking across all networks, technologies and services. As a result of this approach and the joint venture with Swisscom ICS, Belgacom International Carrier Services is now the 9th largest wholesale voice carrier and a world leader in mobile data transit services. www.belgacom-ics.com

About Sonus Networks

Sonus Networks, Inc. is a market leader in IP communications infrastructure 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 Westford, 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 our Annual Report on Form 10-K for the year ended December 31, 2007 and all subsequent Quarterly Reports on Form 10-Q, 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 Company's ability to align its cost structure with market conditions, 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 restatement of its historical stock option granting practices and accounting including regulatory actions; actions that may be taken by significant shareholders; risks associated with our international expansion; and the impact the current global financial market conditions may have on the telecommunications industry. 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, except as required by law.

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