Friend of mines bought a jailbroken iPhone 3g off Ebay, they thought i was jailbroken/unlocked but the phone will only read at&t simcards even after unlocking it with ultrasn0w... Phone is iOS 4.2.1 and firmware is 06.15.00 which people say online can't be restored back, so I don't know what the problem is... anyone know a lot about unlocking iPhones and might know what the problem could be?