When your Wifi UMA signal is too weak, it switches over to EDGE, but a lot of the time this causes a problem and results in a call dropping. I get the same problem. You get free calling when calling using UMA so that is why it prefers that. Also I believe when your phone goes into "SOS" mode, this is when you have too bad of a signal for wifi or EDGE, and the phone goes into an "emergency call only" mode, called SOS. Correct me if I'm wrong on the SOS part though.
Last edited by BIOHazard87 : 05-29-2008 at 03:57 AM.