I have jailbroken and unlocked iphone 3G ' s before. Have tried several methods but cannot get a cel signal on this 3GS. Tried it with Pwnage Tool on 4.1 and Ultrasn0w the again with Pwnage Tool on 4.3.1 and same issue....no T Mobile signal. It seems there was a problem before with ultrasn0w 1.2 but the 1.2.1 was supposed to fix this. And looks like it has for most , but not me. I either get the single bar with no carrier or "searching" and nothing. Tried several working sim cards as well. Any clue why this is happening?????