Hi I purchased an iPhone 3G last September with a Pay and Go sim. However, recently, I have found I am spending quite a lot in terms of top ups and have decided it would be better to go for a Pay Monthly sim. http://shop.o2.co.uk/tariffs/SIMONLY/benefits/Online_simplicity_20#Online_simplicity_20 This includes Unlimited Web access. Would there be any complications if I were to go about doing this, or will it simply be a case of changing my network settings on the iPhone to recognise that it is using a contract sim? Thanks for your time.