GNU Gatekeeper (previously called OpenH323 Gatekeeper) is a H323 gatekeeper
which uses the OpenH323 stack.
It is released with the GPL (GNU Public Licence)

A H323 Gatekeeper manages multiple H323 clients on a network
and provides a nice user name to IP mapping.
It also supports a proxy function for networks with firewalls and NAT.

As it follows the H323 standard, it is compatible with H323
client programs including OhPhone, OpenPhone, GnomeMeeting and
Microsoft NetMeeting.

It makes use of PWLib and the OpenH323 stack from Equivalence Ltd Pty

WWW: http://www.gnugk.org/

Also see
WWW: http://www.openh323.org/