Problem with my iPhone?

I live in Salt Lake City, Utah. Even if my phone has full bars and 3G signal I can not send or receive texts, make or receive calls, I can not really do anything. And sometimes, my phone is nearly 2 hours of a shift on receiving anything. As in I'll send people SMS to 12:00 and then suddenly, no other texts come in, although I can still send texts. And then at 2:00 I get all messages, but said their time as 12:02, 12:05, you know? When I would have had. I already tried resetting my phone sometimes does not help. with just resetting the network. Any settings even know what the problem could be? I have not done anything to my phone. Not jailbroken, unlocked. And I still use AT & T as a carrier. I had this problem a long time and I have talked to many AT & T people they have no idea what the problem is, because it no dead zone far from my area.

Can you tell me a number of things is your jail broken phone? Your phone is unlocked and if you use another network, then what came with your phone?

iPhone Launch in Salt Lake City