The BlackBerry Passport has a large 4.5-inch Full HD square touch screen and a touch-enabled QWERTY keyboard, giving you ideal content viewing without compromising portability. Built on BlackBerry's secure BlackBerry 10 OS 10.3.1 operating system, the BlackBerry Passport runs on AT&T's network: the nation's most reliable 4G LTE network and the network that has the nation's strongest LTE signal,2 covering more than 300 million Americans.