One more thought, depending on where you are it's possible that the people in the AT&T store might be slow witted. My personal experience (in Nashua New Hampshire) is that they were fairly tech savvy and knew exactly what to do with a Google Play N5 on a non-contract plan with a BYOD discount. But in some places they are clueless. Explain to them that it's a Google Play N5, not a Sprint N5, and that it came unlocked and that it's fully paided for. Also you should make sure that they give you the BYOD discount. Regualr AT&T plans build in the price of the phone but they do offer a discount if you bring your own device.