AT&T Inc. plans to invest about $3 billion to build up its recently acquired Iusacell mobile phone network in Mexico.

Iusacell announced Thursday that the plan will extend voice and data services to cover about 100 million people in Mexico by 2018.

AT&T spent about $4.4 billion to buy both Iusacell and the Nextel Mexico mobile system between November and January. AT&T said in January that it plans to create the first North American mobile service area covering more than 400 million consumers and businesses in Mexico and the U.S.

The announcement of the Iusacell expansion came at a meeting between AT&T CEO Randall Stephenson and Mexican President Enrique Pena Nieto.