im currently and ATT customer. however i want to buy the iphone 6 straight up. no contract extension or next program. i want to pay the full $749.99 for the 64gb. am i limited to buying just ATT devices or could i buy say a TMobile/Sprint/Verizon device and just put my sim card in seeing as how im buying the phone out of contract? would i get the same LTE speeds/bands from my sim card in a non ATT device? im asking because i thought i read this would work with a Tmobile iphone, however when i called a TMobile store that had the phone in stock he told me that i could not use my ATT sim card in it even if i bought it straight, out of contract.