Although not a well-guarded secret, Vonage formally revealed its use of Sonus Networks’ switching platform this week and said it will be expanding the relationship to accommodate growth in its business.

Vonage has Sonus’ GSX9000 switching platform, PSX Call Routing Server, SGX Signaling Gateway, and Sonus Insight Management System deployed in its New York and Los Angeles data centers.

Now with over 1 million subscribers, Vonage will add an unspecified amount of new gear to increase capacity on its network, particularly for PSTN interconnection.

“This is kind of an incremental capacity expansion for us as we continue to acquire new customers,” said Louis Mamakos, chief technology officer at Vonage.

The suite of products from Vonage provides a SIP end-point into Vonage’s internally constructed call processing infrastructure, Mamakos said.

A spokesperson for Sonus said this announcement represents a significant expansion of the two companies’ relationship. Vonage will be adding Sonus solutions in additional locations in the U.S. and potentially to Vonage’s international markets.

“As we continue to grow, we become more efficient in terms of being able to deploy larger capacity platforms,” Mamakos said. “We get the unit cost per channel to a more attractive level when we terminate an OC3’s worth of TDM capacity as opposed to individual T1 circuits.”