I have an Iphone 3g, I bought it, it was unlocked and jailbroken, for the TMobile service, I stopped using it, because I bought a windows phone. Since I wasn't going to keep using the iPhone, I just wanted to use it for music, I decided to update it, but big mistake, it totally locked me out, it's asking for a SIM Card, an active SIM CARD, that goes with the carrier, I guess AT&T. What can I do, can I unlock it, jailbreak it, or should i just give up, and not use it? I only want to use the phone for music, i don't care about apps, games, or anything else, I just want to use it for music. What can I do, please help.