This has been suggested in another thread http://forums.macrumors.com/showthread.php?t=519106&page=1 Today I did it and O2 seem to be playing ball. Here's what I did 1. Bought an iPhone at Apple Store, signed up to a new 18m contract. 2. Called up O2 iPhone 'specialists' on 2302, gave them my new iPhone number and my old O2 number (that I want to keep). 3. The lady said the old number and account is going to be migrated to an iPhone account and the new sim cancelled, up to 48hrs later. At which point I should put my old sim into the iPhone. I don't think this is something that they're publicising or keen on - the first guy on retentions I spoke to at O2 was very persuasive that it would be quicker for me to upgrade when O2 got stock. He also had the cheek to say that the loyalty I had built up would no longer be recognised!!! Like they've been desperate to show loyalty to existing customers so far Given that O2 doesn't have stock and they don't seem to know when they will, this seems to be a better option. Plus they're very nice in the Apple Store! Edit - The number transferred over today. I did not have an iPhone and I was on the simplicity tariff.