U.S. telecommunications giant AT&T plans to spend an estimated $3 billion in investments to push its two countries-one service business model in Mexico.

The company aims to build the first-ever North American Mobile Service Area that will be available to 400 million people and businesses in both Mexico and the U.S.

After acquiring Mexico's third and fourth largest wireless carriers, the company Grupo Iusacell and the NII Holdings Inc. business unit Nextel Mexico, for $4.4 billion this year, AT&T projects the first phase of its network to reach 40 million Mexicans or one-third of the population in the next six months. Its high-speed network expects to cover 75 million subscribers by the end of 2016 and 100 million by the end of 2018.

The acquisition of both companies put AT&T in second place in terms of revenues and third in terms of consumers in Mexico, behind billionaire Carlos Slim's mobile company América Móvil and Spain's Telefónica.

América Móvil unit Telcel caters to 72.1 million subscribers while Telefónica covers 22.5 million customers as of March. AT&T reports that Iusacell and Nextel Mexico's total subscribers are around 9 million. With Telcel dominating about 70 percent of the market, the company is subject to painful regulations formed to level the competition.

AT&T Chief Executive Randall Stephenson presented the business plans at a recent conference with Mexican President Enrique Peña Nieto in Mexico City. The company plans to build a network in the country that will provide a fast mobile Internet service and boost the economic growth of Mexico.

Beginning next month, Mexican subscribers will be able to use their AT&T plans for messaging, voice and data while in the U.S. They will also be able to use their available minutes to contact family and friends who are active on the AT&T network in the U.S.

The company believes its unique selling point of "one phone, one plan, covering two countries" will definitely increase the number of its subscribers in the future.

Photo: Mike Mozart | Flickr