I've got the iPhone 3G, and decided it's time to give it to my mum and upgrade to the iPhone 4. Currently, my 3G is unlocked and I'm using it with a t-mobile SIM that offers me unlimited texts and internet for a month (3 or 5GB fair usage, can't remember) if I top up by £10 the previous month (I get to keep the £10 too). This is a very good deal! So, now onto the iPhone 4. I have 4 options, get it on contract with either O2, Orange, or Vodafone OR just buy the Phone. Now I need unlimited texts and internet. For £35 a month for 2 years, each of the contracts offer ulimited texts and 600 minutes, however, there is no unlimited internet (like my current PAYG t-mobile SIM). Orange offer 'unlimited' (750MB fair usage, quite low compared to what I currently have), O2 offer a set 500MB, and Vodafone offer 1GB. So it seems Vodafone is the best, unless Orange aren't too uptight on their fair usage policy? Now, my 4th option is to buy the phone, cut my t-mobile SIM, and get the same great offer. I've been doing some maths and have worked out that: iPhone 4 32GB + 2 years contract has a total cost of £219 + £840 = £1059, or £1049 with O2 (on any 3 of the networks, only difference is the network and the data limit and £10 cheaper phone on O2) Now for the iPhone 4 32GB + 2 years topping up £10 a month for my unlimited texts + data on my t-mobile SIM would be £599 + £240 = £839 So, buying the iPhone 4 on it's own and cutting my t-mobile SIM and using it as I currently am with my 3G is cheaper by over £200! However, this would involve cutting the SIM, which could go wrong, and the deal for the SIM was limited, so I cannot get this SIM offer again I believe. I do not care for the 600 minutes, as I will have £10 a month to use on calls alone, and I barley call anyway. This also requires the iPhone 4 to be unlocked, which I'm not sure if it is in the UK. My question is, which of my options should I go for? Buy the phone, cut my SIM and use it and save a lot of money at the risk of it not working at all, or play it safe and get the more expensive contract that has low data allowance. I'm stumped. Edit: I expect lots of tl;dr's! Edit 2: Going to buy a micro-sim adapter tomorrow, try cut my current SIM, then use the adapter to test it in my 3G. If it works, I'll go with that. If not... contract. Is the iPhone 4 factory unlocked in the UK?