Okay, so I've got an iPhone 3GS. I've tried updating to 4.2.1 with the 6.15 iPad basebad and unlocking using the redsn0w + pwnage tool + ultrasn0w method. FOr SOME REASON, it wont' let me use my t-mobile sim card, it says "blah blah this isn't an at&t sim card blah blah you're the devil blah blah" .. wel not exactly that but i'm pissed off so that's what it looks like. Is there any way to fix this? I mean ANY way. Any input or suggestions or advice or expert insight would be extremely helpful. Thank you.