Google Talk Call Signaling

http://code.google.com/intl/zh-CN/apis/talk/call_signaling.html

Google Talk uses extensions to XMPP for voice/video signaling and peer-to-peer communication. Currently, Google Talk’s implementation differs slightly from the draft XMPP Jingle specifications. However, Google Talk is in the process of being updated to be in full compliance with the Jingle specifications.