Level 3 Deploying Sonus Platform for Variety of Next-Generation IP Voice Services

WESTFORD, Mass., August 9, 2001 – Sonus Networks (Nasdaq: SONS) today announced that Level 3 Communications, Inc. (Nasdaq:LVLT) has signed an agreement to purchase network architecture systems designed to support Level 3's wholesale IP voice service.

Under the terms of the multi-year agreement, Level 3 plans to deploy a range of Sonus' voice infrastructure solutions, including the GSX9000 Open Services Switch, the PSX6000 SoftSwitch and the SGX2000 SS7 Signaling Gateway. Level 3 expects to deploy the Sonus voice infrastructure systems throughout its 16,000-mile U.S. fiber optic network.

"Level 3 is widely recognized as a pioneer in the development of softswitch technologies, and is the first carrier to build a completely IP-based network worldwide," said Hassan Ahmed, president and CEO, Sonus Networks. "By deploying Sonus' voice infrastructure solutions, Level 3 will not only have the ability to differentiate their offerings, but significantly reduce the costs of delivering a range of voice services."

"By deploying Sonus' IP technologies into our network, we can deliver new services more rapidly and cost-effectively than we could before," said Jack Waters, group vice president and chief technology officer for Level 3. "This relationship with Sonus underscores Level 3's strong commitment to providing our customers with scalable and enhanced IP voice services."

"Sonus technology also allows Level 3 to SIP-enable the edge of our network that provides voice termination services," added Rob Hagens, senior vice president of Global Network Engineering for Level 3. "Further, the Sonus solutions enable us to scale our network to meet growing customer demand for our IP voice services."

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice infrastructure products for the new public network. Sonus' solutions enable service providers to deploy an integrated network capable of carrying both voice and data traffic, and to deliver a range of innovative, new services. The Sonus Open Services Architecture (OSA) and award-winning Packet Telephony suite cut the time-to-market for competitive new service products, allowing carriers and third-party developers to 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 voice, data and multimedia solutions for implementation in the world's largest networks. Sonus, founded in 1997, is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

About Level 3 Communications

Level 3 (Nasdaq:LVLT) is a global communications and information services company offering a wide selection of services including IP services, broadband transport, colocation services and the industry's first Softswitch based services. Its Web address is www.Level3.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 Sonus' Quarterly Report on Form 10-Q, dated May 14, 2001, 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 Company's ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change, integration risks relating to the acquisition of telecom technologies and manufacturing and sourcing risks.

GSX9000, PSX6000, SGX2000 and Open Services Architecture are trademarks of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.