Sonus Networks equipment helps support the VoIP services delivered by Vonage, the companies say.

For the first time Vonage is publicly acknowledging that it uses Sonus gateways along with Cisco gateways to connect calls between its customers who use VoIP over broadband connections and phones on traditional public phone networks.

The Sonus equipment is already in use in Vonage's New York and Los Angeles switching offices, and may be deployed in other locations, Vonage says. Sonus GSX 9000 and other gear is used to supply OC-3 optical handoffs with the PSTN, Vonage says. The equipment was installed in the network last year.

Other major VoIP providers also use Sonus gear, notably AOL, AT&T and Earthlink.