A technical problem in western Mexico City saturated the Telcel cell phone network, Mexico's largest. The network is owned by Slim's telecommunications giant America Movil, the company said on Tuesday.
"When part of the network loses service, others back it up," said America Movil spokeswoman Patricia Ramirez. "But there was a serious saturation problem and it started to affect other parts of the city."
Telcel has 40 million users across the country. Most severely affected were those in the vast capital and its surroundings, where most of the company's customers are located. Service began returning hours later and was 90 percent functional by late afternoon, Ramirez said.
America Movil controls about 70 percent of Mexico's cell phone market and also has operations across Latin America and in the United States.