February 5, 2006
OpenZoep: An Open Source VoIP Engine
OpenZoep (pronounced "open soup") is a client-side telephony and instant messaging (IM) communications engine. It supports computer-to-computer (peer-to-peer) VoIP calls, instant messaging, and outbound PSTN and SIP calls to free and premium SIP providers. OpenZoep is available under the GPL license, as well as a commercial license for companies that do not wish to publish the source code of their commercial products based on OpenZoep.
Link: O'Reilly Network