OpenH323 is a multi-platform H323 Video Conferencing program.
It can exchange full duplex audio and video with other H323
compliant video conferencing programs including Microsoft NetMeeting
It requires a sound card for audio support and a Bt848/878 based
video card (using the bktr driver) for video capture.

It makes use of PWLib.

PWLib is a multi-platform code library that can be used to write
applications that will compile and run on Windows, Linux and a few other
Unix variants. It was developed by Equivalence Ltd Pty

For more information see
http://www.openh323.org
http://www.equival.com