Shares of AT&T are up by 0.69% to $35.15 in after-hours trading on Friday.
The proposed transaction will create the "first-ever North American mobile service area to cover 400 Mexico and U.S. consumers and businesses," AT&T said in a statement.
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As part of the deal, AT&T will gain all of Iusacell's wireless properties, which includes licenses, network assets, retail stores, and approximately 8.6 million subscribers.
Grupo Salinas currently owns 50% of Iusacell, and the AT&T deal will take place after the close of Grupo Salinas' current purchase of the other 50% of Iusacell.
Iusacell offers wireless services under its Iusacell and Unefón brand names. The network covers 70% of Mexico's approximately 120 million people, and AT&T plans to expand the network to millions of additional customers, the company said.
"Our acquisition of Iusacell is a direct result of the reforms put in place by President Peña Nieto to encourage more competition and more investment in Mexico. Those reforms together with the country's strong economic outlook, growing population and growing middle class make Mexico an attractive place to invest," AT&T CEO Randall Stephenson said.