Help a noobie out! Need to unlock my iPhone 3GS ASAP

[Shevchunko]

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!

 

[dwfw]

Two words: Gevey SIM. Now, go to Google.

 

[Shevchunko]

As far as I can see they're only for iPhone 4 unless you use a mSIM > SIM adapter held together with tape...

Tried to recover to 4.1 and now it just goes to the connect to iTunes screen (but now with the old iTunes logo not the one on 4.3.5) but I have to go to work now so i'll get this sorted tonight.

Any help is massively appreciated!

 

[liquidzoo]

Has this phone been jailbroken in the past?

If so, you might (depending on if you can get the shsh with TinyUmbrella) be able to roll back to 4.3.3 and perform an untethered jailbreak/unlock on it.

If not, you will not be able to roll back at all. You will be stuck on 4.3.5 and any jailbreak you do will have to be tethered.