opensource videoconference soft

Question

I am looking for a piece of open source software or library which can do the following:

1. Working a mux on client side (like a Skype/iChat videoconference (more than two callers at a time))
2. Supports STUN or another NAT traversal mechanism.

I don't need BigBlueButton, WebEx, or their analogues.

Answer 1

http://www.h323plus.org/ - an open source H323 library.

http://opensips.org/ - open source SIP.

Covers both major standards.