I have a full sized SIM from a work phone that I have used in my last two iPhones. This account is paid for so I want to cut that SIM to put it in my iPhone 4. It was easy last year to activate the 3GS with a new number (I later put that SIM in my 2G iPhone and gave it to my daughter), swap SIMS and then everything worked fine. With the smaller SIM slot, I am not so confident. I know that people have cut full sized SIMs and put them in iPads, but I don't want to mess up my SIM since it might be tough to get another one from work. Anyone know? I have looked at the tutorials online, but the iPhone 4 contacts look a little different than the ones I am seeing.