BUMP? Any ideas out there?? Or is this site more for software then hardware?
It is a challenging question because the reality is you would have to ask an engineer. In theory it should work but the coding is different and that coding gives the device the permissions to access certain towers. If it does work I would not be surprised if you were unable to access lte as att will allow unlocked phones to access hspa + but not lte. And like any carrier they will protect their lte bandwidth so it may not be as easy to get that information especially from att who lost a lot of smart phone customers when they could not keep the iPhone connected to 3g. That black eye probably made getting access to att lte as tough as accessing VZW lte network.