How do I use a microphone in Diablo 3?
NO, there is no Voice-chat (yet) in Diablo3
"There is no built in voice chat, at least not for ship," Bashiok said. "If we try voice chat in another game we want to make sure its worth using."
Sources G4 Twitter
You can talk with your friends using a third party technology such as:
- Ventrilo for its ease in finding and buying a hosted Vent server.
- Team Speak, the most common Vent alternative.
- Skype is popular because many gamers have it already and no server is needed.
- XFire for its integrated IM and social networking platform.
- Mumble because it is free and open source.
Source
You can also use Steam (if you have it). Most gamers have a Steam account, I've found, and it's actually pretty decent voice chat quality.