Originally Posted by
gfunkdave
Then it's a setting in AT&T's SIM card that checks if it's been put in an unlocked phone.
The Carrier menu visibility is controlled by the SIM card. It has nothing (directly) to do with whether the phone is SIM unlocked.
Nope. Nothing to do with the SIM. Carriers other than Verizon can prevent the phone from another network. Best Buy carries one model iPhone. Once activated on any carrier other than Verizon, the phone is locked to the carrier until an unlock request is submitted to the carrier. Verizon can not lock LTE phones.