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Latest Round Brings Total Funding to $46 Million

WESTFORD, Mass., December 15, 1999 - Sonus Networks today announced the company has closed its $23 million third round of private financing. The latest round of funding will fuel Sonus' drive to become the leader in providing carrier-class packet telephony solutions. Sonus' solutions reduce service providers' total cost of network ownership and facilitate the creation of new revenue streams through the delivery of new services, enabling carriers to become more competitive. 

New investors in this round include Global Crossing Ventures, the venture capital arm of Global Crossing; Williams Communications; Japanese distributors Mitsubishi Corporation and Nissho Electronics Corp.; and Korean distributor Samsung Corporation. They join the earlier group of investors, including Bedrock Ventures, Bessemer Venture Partners, Charles River Ventures, Matrix Partners, and North Bridge Venture Partners, who contributed additional capital to their original investments. The investment group now combines leading carriers and international enterprises with some of the telecommunications industry's most successful and respected venture capital firms. 

"Sonus is on a fast track - building out our product offerings, growing our infrastructure, hiring the industry's best and brightest, and signing up leading carrier customers," said Hassan Ahmed, Sonus' president and CEO. "Fundamentally, what we're doing will change the way the world communicates, and this new round of investment will further enable us to meet the tremendous opportunity this explosive market presents." 

About Sonus Networks

Sonus Networks, Inc. is delivering a new class of carrier solutions that enable the movement of telephony to converged packet networks and the development of a new generation of innovative voice and data services. The award-winning Sonus Packet Telephony suite and Open Services Architecture^TM (OSA) cut the time-to-market for competitive new service products, allowing carriers and third-party developers to sustain and expand marketshare, and build important new revenue streams. Its highly scalable products fully interoperate with and extend the life and utility of today's public network. Sonus embodies in its management and staff decades of experience in developing carrier-class solutions at companies such as Cisco Systems (Nasdaq: CSCO), Lucent Technologies (Nasdaq: LU), Nortel Networks (NYSE: NT). Sonus, founded in 1997, is headquartered in Westford, Massachusetts and is privately held. Additional information is available at http://www.sonusnet.com. 

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