Completion of OSMINE Signifies Interoperability with RBOC Networks

WESTFORD, Mass., January 2, 2002 – Sonus Networks (Nasdaq: SONS) has scheduled a conference call for Wednesday, January 16, 2002, at 5:00 pm EST to announce its Q4 and FY2001 financial results. Financial results are expected to be issued after the close of the market on Wednesday, January 16, 2002.

Date: Wednesday, January 16, 2002

Time: 5:00 pm EST

To listen via the Internet

Sonus will host a live webcast of the conference call. To access the webcast, visit www.sonusnet.com, Corporate, Investor Relations.

To listen via telephone

Dial-in number: +1-888-293-1197

Replay

A telephone playback of the call will be available following the conference and can be accessed by calling +1-800-633-8284 or +1-858-812-6440. The reservation number for the replay is 20166153. The telephone playback will be available through Wednesday, January 30, 2002.

The webcast will be available on the Sonus Networks Investor Relations site through Wednesday, January 30, 2002. To access the replay of the webcast, visit www.sonusnet.com, Corporate, Investor Relations.

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture(TM) (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services. Sonus' award-winning voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide. Sonus, founded in 1997, is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.