AT&T Unlock Says “Not an AT&T Device” — IMEI Mismatch Fix (2026 Guide)
TL;DR — Quick Answer The “not an AT&T device” error means AT&T’s system doesn’t recognize your phone’s IMEI number in their database. This commonly happens with BYOD (Bring Your Own Device) phones, refurbished or second-hand devices, and phones that had their IMEI swapped during an Apple or carrier replacement. To fix it, first double-check your … Read more