This is my first smartphone so forgive me if I've got the basics wrong. assumption:3G is for data, which is separate from actual phone use which uses the cell network. I had the mobile network turned off, which turns off the 3G radio(assumption). I tried to make a call, going through google voice, and kept getting messages that it couldn't connect to the server(don't remember actual message), but I had a good cell signal. When I turned back on the mobile network I then was able to place my call. Do I have some assumptions wrong here, or does google voice have to use 3G/Wifi for something? I don't see that it would, but it seemed to in my case.