I have an old AT&T iPhone 3G iOS 4.2.1. Does anyone still know how to jailbreak and unlock this to work with T-Mobile? Will the new Envasi0n work? What is the easiest way, I'd prefer not to have to download an entire iso to jailbreak but will if needs be. And do I just install Ultrasn0w from cydia after jailbroken to T-Mobiate?