From July 15, T-Mobile customers will be able to use their smartphones in Canada and Mexico without incurring any roaming fees. The new program, dubbed Mobile without Borders, applies to incoming and outgoing voice calls and text messages as well as the use of 4G LTE data.

According to T-Mobile, 35 percent of all international calls and 55 percent of all international travel from the US last year was to Canada and Mexico. T-Mobile also claims that collectively, carriers generated nearly $10 billion in global roaming charges with profit margins of more than 90 percent.

Outspoken CEO John Legere announced the new program for Simple Choice customers in a video blog earlier today. Predictably, much of his spiel involved bashing rival AT&T.

As you may recall, AT&T has purchased two major Mexican wireless providers this year: Iusacell and Nextel Mexico for $2.5 billion and $1.875 billion, respectively. Part of AT&T's motivation for its expansion into Mexico would be to offer cross-border coverage for US-based customers but that hasn't yet happened.

The move is part of T-Mobile's new Uncarrier Amped campaign in which the company is improving some of its earlier Uncarrier programs. The first Amped promotion, Jump On Demand, debuted late last month and allows customers to upgrade their smartphone up to three times in a year. T-Mobile eliminated international data roaming and texting fees in October 2013 although data was limited to 2G speeds.

In related news, T-Mobile revealed it added 2.1 million customers during the second quarter. That's an increase of 41 percent year-over-year and once again serves as proof that its disruptive Uncarrier tactics are working. T-Mobile's total customer count now sits at 58.9 million, just ahead of third-place Sprint which finished with 57.1 million customers in the first quarter. We won't know if T-Mobile's new additions are enough to pass Sprint until the latter company announces its latest subscriber numbers during its upcoming earnings call.