Hey folks. I've been trolling around the web for a few days now trying to find the solution to this problem, I've read a hundred threads, and the answer still entirely escapes me. I've tried everything that I can think of, and almost everything that other people could think of. The situation is thus: I have an iPhone 3 with 4.2.1, carrier is AT&T 9.0, 5.15.04 firmware. It was given to me by a friend after my last (contract) phone died, and I got a GoPhone SIM, jailbroke/unlocked with redsn0w/ultrasn0w, activated the SIM using an IMEI from another (non-iPhone) cell which I found online, not sure the type of phone, registered for service online, and had myself a working smartphone with voice/text. Great. But, of course I'm a dumbass, and I've never had a smartphone before, so I was unaware of the way in which apps will drain battery life if left open. I woke up one morning to find that my phone had died. No problem, right, I'll just plug it in and it'll be fine. Nope, **** you, no service. I messed with it for a few hours, switching airplane mode on/off, resetting the network settings, re-loading ultrasn0w, rebooting it, everything. Out of nowhere it started working again - I am still unsure as to whether I did something that fixed it, or whether something else was going on. Okay, so, of course I forgot about the apps again, phone dies again. This time it's been... 3 days, 4 days? I've since done everything that I did before to try and fix it; I restored the phone to its original OS, jailbroke it, unlocked it, inserted the SIM, still no service. I'm not particularly stupid and I've always been good at isolating variables in troubleshooting technology, so I don't think it's an obvious quick fix, but maybe it is, I'm stumped. Can anyone shed some light on what's going on?