You can use Teamspeak.
I will even give you a free 30 slot Teamspeak server with admin access if you like.
Download
Teamspeak client.
All your members will need to download it as well.
Then install
TeamSpeak Display/Login Module
You will need to follow link it bigjohnny's mod to down load it.
Working Demo links there as well.
If you don't use vbadvance, no worries. This can be used with side columns on regular vbulletin.