I have an iPhone 3GS, purchased in March of this year. It's worked great except one thing: twice so far my phone has been displaying full bars and EDGE while my mom's iPhone 3GS displays full bars and 3G. When this happens, I can make phone calls and send text messages, but I can't get on Safari or anything else that uses data. The first time this happened (about a month and a half ago), I just turned off my phone, removed the SIM card and put it back in, and let it sit, turned off, for about an hour. Then when I turned it back on, it was fine. This time, I have tried that to no effect. It's not simply that I have bad coverage where I'm at or no 3G because my mom's phone works fine. I recently updated to 4.0.1, if that makes any difference (my mom has not). Is there any fix for this I can try myself? Or should I take my phone into AT&T and let them deal with it?