i had it on my replacement verizon iphone 5 at the apple store. its only on CDMA phones as far as i know. its because they all operate on the same frequencies (pretty sure) so when you select the carrier, it will lock it in to them. it makes it easier for apple to be able to carry "blank" replacement phones which can be programmed on the spot. since they dont brand the phones by carrier, it allows them to lock the generic blanks to whatever CDMA carrier is needed, it then just locks in the carrier programming. i can see where this makes perfect sense from a logistical standpoint. apple can carry 500 blank CDMA replacement phones as opposed to 200 verizon, 100 sprint, 50 of another carrier.....etc etc.