OpenH323 is a multi-platform H323 Video Conferencing library.

This is used to make H323 Video Conferencing applications
like GnomeMeeting and ohphone. (both in the FreeBSD ports tree)

The library includes a sample program called simph323.

The OpenH323 library makes use of PWLib. http://www.equival.com
PWLib is a multi-platform code library that can be used to write
applications that will compile and run on the BSD Unixes, Windows, Linux
and a few other Unix variants. It was developed by Equivalence Ltd Pty.