Usually when I play with my friends and we voice chat, its a small set of us which play. It’s usually 3-4 core friends, with the guild. While this post isn’t really aimed at the players who need voice chat for their guild, it is aimed at those 3-5 players who want great clarity, without the lag spikes which Skype can create..
Razer Comms is a VoIP program which allows you and a group of friends to connect over a server with hotkey and GUI overlay support. Because it’s server hosted, this means it won’t cause any lag spikes, which can disrupt game play, or even the chat itself, which DOES happen if you use Skype (on the host’s computer).
Of course if you are looking for the guild chat, where the whole guild can get on for a raid or PvP, then you will instead want to check out the Mumble Servers here. At 15 cents a slot, the cost is next to nothing for a large sized guild. If you prefer Team Speak, those are available as well!