VMUKTI

Description
The core Platform Features Include:

Audio/ Telephony, Multipoint Video, Chat, File Search, Whiteboard, File-sharing, Presentation, Remote Monitoring & Controlling, Co-authoring, CRM, and more

In other words VMukti for you could be:
A Simple Distributed VOIP Unified Communication PBX Network Software
A Rich Media Collaboration enabled Social Networking Software
A P2P Based Video Conferencing/ Web Meeting Platform
A Mashable Communication Platform that allows extending by development of 3rd party Widgets
VMukti is built using next generation .NET 3.0/ 3.5 technologies including WPF, WCF, IPv6 and P2P.

And Best of all it is Open Source.