I've got 2 iPhone 3G's, both 4.2.1 and baseband 05.15.04. One of them I've had for a few years and has been jailbroken and unlocked for a while, I restored it to re-jailbreak it (It was getting slow and crashing all the time) and now I can't get it to unlock again. Ultrasn0w won't finish, it just gets to a certain point and hangs. I've restored and re-jailbroken with pwnagetool multiple times, the result is the same. The other phone hasn't been jailbroken before. I'm trying to get either of them to work so I can put any sim in it. I don't know if at some point I screwed up the one iPhone irreparably while jailbreaking it wrong at some point, so I'm reluctant to try to jailbreak the other before I know for certain what I'm doing wrong. So, has anyone ever had a problem like this before with Ultrasn0w? Any advice or other guides to unlock a 4.2.1/05.15.04 iPhone 3G? I'm on a mac but if there's a method of jailbreaking and unlocking that requires a PC that'd be ok too. Any help would be very, very much appreciated.