I'm running out of ideas. I got myself an AT&T iPhone 3GS yesterday. I have T-Mobile. I've jailbroken it with redsn0w, installed p0sixspwn to untether it, and ultrasn0w. I'm on 6.1.3. I WAS on 05.13.04 and was getting a No Service message with 3G turned off, Airplane Mode switched on and off several times, and resetting the network settings. After more Googling, I read that only 06.15.00 works on 6.1.3, so I flashed to that and I'm having the same problem. Is there anything else I'm missing? I've put almost 12 hours into this total, and the problem is every time I do research, I get different answers about what firmware and baseband I should be on. I'm currently on 6.1.3 untethered with p0sixspwn running ultrasn0w 1.2.8 and 06.15.00 baseband. I don't know if this means anything, but it does show T-Mobile as my carrier in my settings. It says T-Mobile 14.2.