just real quick and simple I have had problems with my cellular antenna strength on my 3gs since day one Apple exchanged the phone. I went to AT&T exchanged my Sims problem appears to be solved, I have waited since yesterday no major signal strength fluctuations. this cost me 20 minutes of my time and $0. Those that are having this issue I would try it regardless of carrier. oh yeah I took my jail broken phone in all customized AT&T didn't say a word.