Well today I just learn that a iPhone 5 SIM card will not work with a iPhone 5s. Yesterday I was at a sprint store trying to activate a iPhone 5s replacement from Apple but it keep saying uncompatible with the sprint. ( we tried 8 different ones) So I go back to the apple store. They tried another SIM card and the same thing. And then another employee said that not the right SIM card. The manger said oh yea. Go to back and get the new iPhone 5s SIM card. So if u buy a use iPhone 5s make sure it the new one for the 5s.