Hello everyone, I have had this issue which I could not find anything online about. I currently have two iPhone 3g and one iPhone 3gs which have been upgraded to 4.1/4.2.1 with baseband 5.14.02. After it upgrades, none of them accepted the original ATT SIM or any SIM from ATT. Once the phones were plugged in to iTunes, it would say "SIM is unsupported". I tried Jailbreaking them once more, and hacktivating but these efforts did not resolve the issue. Eventually, I had to use Redsn0w and upgrade these phones to BB 6.15 and unlock with UltraSn0w in order for them to work with the ATT SIM. Hopefully these phones don't continue to have issues for their users, but has anyone run into this same issue? It seems really strange to me that the stock firmware and ATT SIM would not work.