T-Mobile's next Uncarrier move will likely give AT&T execs a massive migraine. It's called "Mobile Without Borders" and it basically lets T-Mo users use their service in Canada and Mexico at no extra charge. The reason why AT&T won't like it is they have spent billions buying up Mexican telecoms, and promising that AT&T will be "the first seamless network covering Mexico and the U.S.,’ something ‘unique’ that ‘nobody else will be able to do for the consumer." Obviously, T-Mobile beat them to the punch, although T-Mobile won't have 100% coverage in Canada and Mexico. The fact that T-Mobile will not charge any extra for this service must be especially irksome to AT&T. Under the "Mobile Without Borders" initiative, T-Mobile's coverage and calling area will now extend into both Canada and Mexico for all Simple Choice plan customers. Calls to Canada and Mexico are now included in the standard plan, as is roaming within both countries. You can watch John Legere explain the new program in the video above, and we have the full press release in the thread below. How many of you folks have friends or family in Canada and/or Mexico to take advantage of this new initiative from T-Mobile?