Can an unlocked sim-free Japanese iPhone 7/+ work in the US? I plan to buy one in Japan next week because they have the Suica embedded in the phone. OR should I just buy one at the Apple store before I leave? I would have waited for the 8, but my battery is slowly dying. Drains on a full charge in just a few hours (less than 3-4 on my 6+). I plan to buy an unlocked sim-free Japanese iPhone at an Apple store directly cause carrier ones are locked. Can it work with my carrier (i'm on ATT) in the US when I take it home? Anyone know? Thanks in advance.