I'm in the military and moving to Japan in a couple of months. Does anyone know if I can use my unlocked AT&T iPhone in Japan with AU KDDI? I don't want to use softbank because I hear that their service is not as good. I also don't want to buy an new iPhone 4S, when the iPhone 5 is probably going to be coming out very soon. Will AU let me just get a sim card on contract with them? I'd be grateful for any info that I can get. THANKS!!!