Japanese Iphone 5 work with verizon att&t or anyother US service providers

[ctills15]

Hi I'm in the military and currently stationed over seas in okinawa japan. I decided to buy a cell phone while i was here and chose the iphone 5. I am with the AU cell phone carrier now and and curious if i can use this phone with a US sim card when i get back to the United States. I am also trying to get one as a gift for a family member and am not sure if this phone will work with an american carrier. I can unlock it if that will do that trick. Not sure where to start or if its possible. Any advice or insight would be greatly appreciated. Thanks, Chris