Libjingle is a set of components provided by Google to interoperate with Google Talk’s peer-to-peer and voice calling capabilities. The package includes source code for Google’s implementation of Jingle and Jingle-Audio, two proposed extensions to the XMPP standard that are currently available in experimental draft form.
"Tapioca is a framework for Voice over IP (VoIP) and Instant Messaging (IM). Its main goal is to provide an easy way for developing and using VoIP and IM services in any kind of application."