Currently I have an iPhone 3GS on O2 network and have just received my new iPhone 5 from T mobile (as I want to transfer to them). I was advised to call T mobile with the PAC code from O2 once I had received my new iPhone 5 so that they could transfer my number to them and that this should take 1 or 2 days. I am therefore going to call them in the morning to do this. I therefore want to ask whether I should wait for T mobile to transfer my number over to them before I plug my iPhone 5 in to my macbook and sync it with iTunes in order to put all my contacts, apps, photos etc on it or if I should just plug it in now and the phone number will just change once T mobile put my original phone number on the account. How will iCloud work as if I plug my iPhone 5 in and sync it then I will have a T mobile phone, presumably using iCloud, as well as continuing to use my old O2 iPhone 3GS for a few days which is also currently set up to sync with iCloud. Any help would be much appreciated!!!