DirecTV sends out such signals about twice a month, but according to The Carmel Group's Sean Badding, intrepid pirates can effectively block ECMs using devices called emulators, or if that fails, reactivate a "burned" card using a "card strip box" that connects to a personal computer.

FORBES: DirecTV Declares War On TV Pirates

As a portable and truly personal computer, indeed, the mobile phone may turn out to be the credit card, or even identity card, of the future, making payments and opening doors.

ECONOMIST: Walking on air