The outage knocked out cellphone service for thousands of its users across the U.S. starting early Thursday before it was restored.
AT&T blamed the incident on an error in coding, without elaborating.
“Based on our initial review, we believe that today’s outage was caused by the application and execution of an incorrect process used as we were expanding our network, not a cyber attack,” the Dallas-based company said.
Outage tracker Downdetector noted that outages, which began at about 3:30 a.m. ET, peaked at around 73,000 reported incidents. AT&T had more than 58,000 outages around noon ET, in locations including Houston, Atlanta and Chicago. The carrier is the country’s largest, with more than 240 million subscribers.
