I don't understand too much of this but I have a question. My daughter bought a locked un-jailbroken 3G w/3.1.3 firmware. We use t=Mobil, so obviously we have to jailbreak & unlock it. What I am reading online says I have to downgrade the firmware to 3.1.2 before I do anything or it will revert back to locked at some point. How do I do this? do I have to insert her sim card from tmobil before I do it? Right now when I turn it on all I get is "no sim card installed" & an itunes icon. Or is there someone on here who can do this for her? If so, how much? Help.