I use C3 and I have Teamspeak as a back up.
With C3 voice chat it doesn't use much CPU and you can create many rooms, no server needed, and each room can have a phone number if you need people to join via cell phone.
Yancy and I tried this and we were broadcasting on Twitch and it worked fine. I like to just download C3 and use it, I can make my own WGT related skins for it and it's easy to use.
Free text chat services like Chatzy* are available, free and easy to use and it's basically a few clicks and you're in a text chat room.
*
http://www.chatzy.com/