Self explained: Did AT&T unlock your iPhone? Beware of updates, they might just kill your unlock. From what info I've gathered from the AT&T reps these are the facts. 1. Many people have lost their unlocks 2. Call AT&T again, give them your old case #/IMEI, and they'll re-unlock your phone. Overall, this happened to me after updating to to 5.1.1 from 5.0.1, beware, and call to make sure your unlock is still active (1-800-MY-APPLE). I called AT&T, and was lucky enough to be understood and the re-unlocking process was seamless, my phone is now re-unlocked.