a few links here . . (Score 2, Informative)

sorry, this is what I meant to type in . . http://www.voip-info.org/wiki-VoIP+Training Asterisk is worth looking into - install if you like. It is compatible with sip and cisco's "skinny" protocol and works with cisco phones as well as many others. It also does h.323 (if you like pain), iax2 (used by some big companies such as VoicePulse), adsi, sip, etc. http://www.voip-info.org/tiki-index.php?page=Aster isk You can download an iso and install it from the iso or run from a live cd: http://www.voip-info.org/wiki-Asterisk+installatio n+tips all above are from http://wwww.voip-info.org/