Mumble is an open source VOIP software. We run a mumble server for gamers' VOIP needs. The server is free to use for everyone.
Server : mumble.polygame.fi (pauli.polygame.fi)
Riba. If something doesn't work, bug him.
Using version bundled with Debian.
When migrating service, transfer /etc/mumble-server.ini and /var/lib/mumble-server/mumble-server.sqlite files.