While still in contract with 3UK I wanted to see if I could get an iPhone and make it work with my existing contract. In the process I fell foul of the unlocking scam sites (and I'm careful about this stuff) finding that they simply provided jailbreaking software that was freely available anyway.

After reading hundreds of forum posts I found a way and now have a lovely iPhone 3GS working on 3UK. Here's how I did it.

O2, bless them, unlock Pay As You Go (PAYG) iPhones for a nominal fee and without question so...

1.Get yourself a locked O2 iphone (I got mine from ebay)
2.Get an O2 PAYG sim, any will do, don't be fooled by the salesman who tries to sell you an iPhone specific sim at a premium, you don't need it for our purposes
3.Top it up so there's over 15 credit
4.Call two numbers (you'll need them at the next stage)
5.Go to https://www.o2.co.uk/apps/help/help?qid=1&q1=2&route=unlocking&case=Handset%20Unlocking%20Form and fill out the form. Remember, you must have 15 credit
6.Wait a couple of days and you'll get a text saying that your iPhone is unlocked
7.Sync your iPhone with iTunes and the glorious unlocking will be confirmed
8.Make sure you have an unlimited data plan with 3UK though as you'll need it

Your phone will be either fully or largely functional at this stage. Either way it will be completely useable and you will be able to update the software any time you like as it is fully unlocked. You can then use iTunes to upload a custom carrier file (this puts in all the settings and even gives you a Three logo). Just Google for "3UK custom carrier file"

So there you have it. Typical that the iPhone 4G is now out but "hey-ho" I love my iPhone!