So I might be going back to Hong Kong for a 9 day holiday during Christmas time Please Register or Log in to view images And well, I might buy an iPhone 3GS there. Just a few question that I keep thinking about.. When I buy one there, they are already unlocked (to my knowledge). I've heard that once you put in your SIM, it automatically locks onto that SIM carrier. Is this true? Would 3G still work if I bought it back to the UK?