Hey I just bought a iPhone 3GS off a friend of mine, he upgraded it to 4.3.5 (Which I have now found out makes this all a lot more difficult...) and it's on baseband 05.16.02 locked to O2 UK. My main requirement is to get this phone unlocked to accept my T-Mobile UK SIM. Just tried jailbreaking but got nowhere (Couldn't get the hang of tethered booting) so now I'm restoring it back to 4.3.5. So, in pretty easy to understand terms can someone show/tell me or link me to somewhere which will show me the easiest method to get this phone running on T-Mobile? Thanks! EDIT: I've read through pages of threads and tons of blogs, but still can't figure out what to do... I was trying to downgrade to 4.3.3 which is why I tried the jailbreak but the tutorial I was following wasn't much help. Anything is appreciated, desperately need to get this working!