I just ordered an ipad 2 w/ wifi and 3g from walmart for $399. It's advertised as having 3g from verizon or at&t. When you purcase it it does'nt ask which 3g provider I want to use. Does anyone know how this works? I'm not going have to order one of those 3g "pucks" with a cupon that comes in the package after I get my ipad am I?