AT&T Users Upgrading: Shut Off Wi-Fi Calling First

When upgrading to a new iPhone, be sure to shut off Wi-Fi calling first, if you have it enabled.

AT&T associates Wi-Fi calling ability with the phone itself, so if you do not shut it off before upgrading, you will need to call AT&T and have them delete Wi-Fi calling from your profile (and will need to reboot your phone) before you can enable Wi-Fi calling on your new phone, otherwise you will receive an error pop-up telling you to contact AT&T.