My family has hosted a Nigerian young man for the past two years & he is about to go back home. He's got an AT&T iPhone 5s that we gave him when he first got here but I never had it unlocked & I don't have the original sim. I'm looking at unlock options but wanted to be sure that if I do get it unlocked, that it will work in Nigeria. I believe that current iPhones (6 & 6s) will work anywhere but I don't remember if that was the case for the 5s iPhones. Does anyone know?