I'm keeping a pinch of salt close to hand for this one.  TUAW reader AJ is claiming that, by taking his AT&T prepaid SIM into a store run by UK carrier Vodafone (inside an O2 XDA smartphone), the staff there were able to reassign the SIM's serial number to his existing Vodafone account.  Then, back home, he quickly stuffed the AT&T card back into his iPhone and had the handset working on the UK network, with his UK number but no visual voicemail

Response has been, unsurprisingly, mixed, with some excitedly planning to try the same themselves while others cry fake and point to what are, to be fair, a number of unusual aspects to the story.  For a start, why wouldn't Vodafone just give him a new SIM card rather than port over the old one?  Is it even possible for the system to accept the full serial number, when some claim only the last nine out of the full twenty digits are changeable on the carrier's computers?

So we're not saying it's impossible - in fact, given the iPhone uses a check to make sure the SIM card it's using is from AT&T before it will allow service, as long as you could get another operator to use that card then it should unlock the handset - just wondering whether it's particularly feasible.  People familiar with rival UK network O2's systems are saying that the exploit wouldn't work with them, seeing as they're limited to those last nine numbers to change.

Is there anyone else in the UK with an iPhone planning to try this?  If you do, make sure to let us know in the comments!