How do I unlock an old IPhone so that it can be used by a different carrier than was originally used on phone
How do I unlock an old AT&T IPhone to be used by a TMobile SIM card
iPhone 8 Plus, iOS 14
Question marked as
Go to Settings->General->About->Carrier Lock. If it says its restricted there, then you will need to contact AT&T and request they unlock it.
See here: link-> How to unlock your iPhone for use with a different carrier - Apple Support
and here: link-> https://www.att.com/deviceunlock/