I had to purchase a new cell phone. I went to an AT&T store and their price for a new S22 was about $150 more than for an identical, unlocked new phone from a non-AT&T online vendor. I was told by a sales person at the AT&T store that any even unlocked S22 purchased from anyone but AT&T would not and could not work at all ever on the AT&T network. Is this correct?