I just transferred my active t-mobile sim card from a new phone back to an old phone (that used to be active with att). the old phone is displaying the message "sim card not supported", noting it's 'not a hardware issue.' what's up with this? how do I resolve it?
iPhone 7, iOS 10
Sounds like the old phone is locked to AT&T. You’ll need to work with AT&T to get it unlocked to use another carrier’s SIM.
See -> How to unlock your iPhone for use with a different carrier - Apple Support and https://www.att.com/deviceunlock/
Sounds like the old phone is locked to AT&T. You’ll need to work with AT&T to get it unlocked to use another carrier’s SIM.
See -> How to unlock your iPhone for use with a different carrier - Apple Support and https://www.att.com/deviceunlock/
Sim card activation, sim card not supported
