I've decided to get a Verizon iPad Air, but there will be months that I may want to use T-Mobile and some months that AT&T will be better for my use. Will any T-Mobile or AT&T nano sim card work in the iPad? For T-mobile, for example, they seem to have sim cards for tablets ($10) and others for the iPhone (currently free), but I have heard they are the same. The AT&T cards I have seen on Amazon say the are for the iPhone 5.