I just spent an hour on the phone with Apple and At&T because of this. It was going from 5 bars to 2 bars to no service, jump back up and drop off to no service again. All this while I wasn't moving. When I called the Apple rep my call was cracking and dropping while I was outside in the open.
They told me to take the phone back to the AT&T store to get a new one. I hope it works better than this one.
Seems to be the standard for me with cingular/att (been with them for 4 years now). Will go from one bar to 5 in a matter of 5 seconds then stay at 5 bars for 30 minutes or more then do the same thing. Its just an annoyance and unless it happens while youre on the phone it doesn't effect much. Even when i'm on a call at the time it happens it only for 5 seconds anyway--worst case a dropped call and i have to call back.
I have noticed the same problem. The phone is sitting on the table and the signal bars go from 5 to 1... 4 to none..... none back to 5 bars... I called AT&T and their rep told me it is quite common because it's a radio signal and anything in the path of the signal can cause it to change even tree branches...I don't buy that... I have never had that type of problem with any other wireless carrier.