One device, all networks. That's been a fond dream through the iPhone and iPad lifecycle, and while the iPhone 4S remains a unified device (sans 4G LTE support), the iPhone 5c and 5s remain split into CDMA-enabled and pure GSM model numbers.
Enter the new slimness. The cellular-capable version of the iPad Air, like the forthcoming iPad mini with Retina display, actually ships in only one flavor: universal LTE. All the US carriers, major and minor (Bluegrass? Aio?) support wireless on the device, and it s