if not sure what voicechatter is think as of it as ventrilo or teamspeak but open source and free
VoiceChatter is a free, cross-platform voice communication (chat) application. It was designed with gaming in mind, but can be used for many other purposes.
been hosting it over 2 years now on a 10mb fiber
heres the info for the server i already setup a room for DM,COOP,CTF matches
ip:12.176.15.150 port 7878
http://sourceforge.net/projects/voicechatter/files/VoiceChatter%20Client/1.5.0/
