How do I join a voicechat on World of Warcraft?

Well, out of danger of having my comment removed as well…. From what I remember WoW does not have its own voice chat system. My friends that were really into it used a 3rd party chat system and to communicate. If they built one into WoW you will have to join a channel inside the program somewhere. Try talking to other players, or guild members if you are in one.

@b, WoW did, as far as I know, get voice chat as a part of one of the major upgrades.

It looks to me that this official page will have all the info you need.

Obviously I have not played WoW in a long time…

I’m not sure about built in features. I know many of them use Skype for conferencing within their groups.

The voicechat in WoW only turns on if you are in a group, I believe.
When it does work, you will see a small audio icon next to the player that you hear a voice from. The problem is, many players do not use the built-in voicechat.

Many players use external programs, specifically Ventrilo. Even then, you will need to see if others have a chat server for Vent, ask for the IP, pass, and port number for the server, and if everyone in your group wants to use Vent.
Your best bet is to wait for someone else to offer for you to join their Vent server.

If you seriously plan to chat vocally with other players in the future, I suggest installing Ventrilo.