I want to sell my iPhone 5 and am going to reset it, as in erase all content and settings, but I had the phone unlocked by AT&T about a year ago. If I reset the iPhone, will the unlocked status on the phone disappear or is it always retained on the phone until a carrier locks it?
iPhone 5, iOS 8.4.1
No. As long as you requested the unlock from the carrier it was locked to, and then processed the unlock through iTunes then it will never lock to another carrier again if restored.
So basically, the phone will never be able to be locked again.
I don't remember processing the unlock through itunes, but I did connect the iPhone to itunes a lot after unlocking it, does that work as well?
No, to process a carrier unlock, you must restore the device as new in iTunes. You'll know the unlock worked as there will be a message in iTunes confirming that once the restore as new is completed - How to unlock your iPhone for use with another carrier - Apple Support
Resetting unlocked iPhone 5, will the unlock be retained?
