I purchased a 5S at full retail from a Verizon store. When I put my AT&T SIM in, I get 4G but no LTE. I called AT&T and was informed that they could not provision for LTE because my phone is a Verizon phone. I know that the hardware is identical as far as LTE band support and that Verizon's phones are supposed to be unlocked. As I understand it, if my phone was not unlocked I wouldn't be able to get any AT&T service at all. So, it appears to be unlocked but not permitted to get LTE. Anyone run into this issue? If so, is it resolvable?