It looks like things are set to get a whole lot more competitive for Carlos Slim, the man who currently dominates the Mexican telco market. US giant AT&T has had its bid to buy the country’s third largest operator – Iusacell – approved by the Mexican telco regulator.

For the deal to complete Grupo Salinas, which currently only owns half of Iusacell, would need to buy out its JV partner Televisa. The regulator also gave that move the all clear in its ruling so it should be all clear for AT&T to complete the move now.

AT&T first announced the move a month and a half ago, so other regulators might want to be aware that decisions such as this don’t always have to take several months. Iusacell is currently the third largest mobile operator, by subscription, in Mexico, according to Ovum’s WCIS service. It has around 9 million subscribers, behind Movistar with 20 million and Carlos Slim’s Telcel with 70 million.

The approval may have been hastened by the hostile regulatory environment faced by Carlos Slim’s América Móvil, which owns Telcel. Back in July Slim announced he would dispose of some América Móvil assets to reduce its dominance of the Mexican market and get the regulator of its back. Inevitably Slim has dragged his feet somewhat since then, and the regulator is probably happy that he is facing increased competition via another route.

AT&T, of course, has deep pockets and can spend on both marketing and improved infrastructure. If Telcel is still to be broken up the arrival of international companies with the ability to invest should liven the Mexican mobile market up considerably.