I picked up a nice Iphone 3GS with IOS 5.01 and BB 5.16.05. I'd like to unlock it so I can use it with T-Mobile, but since my wife would use it, I am concern with possibility of tethered booting. So before I unlock it I wanted to ask a few questions: 1. If I downgrade the IOS to 4.1 and bump the BB to 6.15 then unlock it, would it be an untethered unlock? 2. I actually started the process (no change the BB yet) and installed IOS4.1 along with Cydia and ultrasn0w, but the phone would not work even with AT&T card (which worked fine before downgrade). All other items including Wi-Fi work fine. Is this normal? I am a little concerned to proceed to iPad BB as I don't want to find out later that there is something else broken or missing. 3. When I try to go back to IOS5 via iTunes restore procedure, it throws an error at the end, that I cannot upgrade from my version of the application. Should I use any special tools if I wanted to go back to IOS5? Thank you for any comments.