What is an Internet voice chat service with little data usage?

I enjoy skype chatting a friend while we play computer games together. However I've lately been pushing the data limit a bit. I hear that skype is a big user of data because of it's quality. What could I use as an alternative? I don't mind about quality, so long as we can understand each other, it doesn't need to be crystal clear.What is an Internet voice chat service with little data usage?
teamspeak and ventrillo

most common ones for gaming. I prefer teamspeak.What is an Internet voice chat service with little data usage?
you may try "yahoo messenger".

trade in value

chuckecheese