Apple instructions to unlock iphone 12 AT&T
I requested AT&T to unlock my son's phone for study abroad. AT&T's response email said to use these instructions from Apple to unlock the device:
Using an AT&T SIM Card:
2. When you have a backup, erase your iPhone.
3. Restore your iPhone from the backup you just made.
Why would he back up and then restore his iphone before inserting a foreign SIM card? What happens if he just swaps out the AT&T SIM card for the foreign one without backing up the phone - would he lose any contacts/etc? He would be swapping the AT&T SIM card back in once he returns to the States.