AT&T says coding error caused network outage, not cyberattack

Thousands of AT&T customers across the U.S. lost cellphone service on Thursday due to a coding error that occurred while the company was expanding its network. The outage lasted for several hours and also affected Cricket Wireless, a subsidiary of AT&T.

Customers of other carriers reported problems as well, but those were likely caused by AT&T users trying to reach them. Some iPhone users saw SOS messages on their status bar, indicating they could still make emergency calls.

The Federal Communications Commission, the Department of Homeland Security and the FBI contacted AT&T about the outage, and lawmakers on Capitol Hill said they wanted to understand what caused it and how to prevent it from happening again. AT&T said the outage was not a cyberattack and that it was resolved by the evening.