Ashes of Anduril uses Mumble for the guild's voice chat. It's similar to Ventrilo and Teamspeak, but it has some interesting features making it perfect for a WoW guild.
This is the connection information for our server:
Server IP: 85.236.97.19
Server Port: 3837
After you have connected, you can register yourself on the server through the self menu at the top of the window.