I put in an unlock request to ATT for my iPhone 6s because I am selling it in wake of getting the iPhone X. I just got an e-mail that my request was approved. But I am confused. Do I need to do anything else? In the e-mail it says if I have an ATT SIM do a backup and restore. If I have a non-ATT SIM just insert it. Do I have to do anything besides resetting my phone before selling it? It should be unlocked without me doing anything more, correct?