Because apple changed the size of the sim, there will be swapping issues across the board for everyone that upgrades using a different line. Does anyone have information on how things may go? For Verizon, I'm assuming the nano sim is attached to the line that you used to upgrade ( unless you did a transfer upgrade before the order). I'm guessing you will need to get a new nano sim in order to swap lines? For AT&T, will it be the same? I'm guessing the nano sim will be attached to the line used to upgrade and the nano sim. Should you want to swap with a different line, you will need two new sims ( a nano for the line that didn't come with the 5 and a older sim for the upgraded line) Sprint, I have no clue.