The FCC has released its report AT&T’s outage in February, one that lasted for roughly 12 hours and blocked millions of calls.

According to the FCC, some 92 million calls were blocked during the outage, including more than 25,000 attempted 911 calls. The agency said all 50 states, as well as Washington D.C., Puerto Rico, and the US Virgin Islands were impacted.

“When you sign-up for wireless service, you expect it will be available when you need it – especially for emergencies,” said FCC Chairwoman Jessica Rosenworcel. “This ‘sunny day’ outage prevented consumers across the country from communicating, including by blocking 911 calls, and stopped public safety personnel from using FirstNet. We take this incident seriously and are working to provide accountability for this lapse in service and prevent similar outages in the future.”

The agency’s investigation revealed the following findings:

• The outage affected users in all 50 states as well as Washington, D.C., Puerto Rico, and the U.S. Virgin Islands. All voice and 5G data services for AT&T wireless customers were unavailable, affecting more than 125 million devices, blocking more than 92 million voice calls, and preventing more than 25,000 calls to 911 call centers.
• Voice and 5G data services were unavailable to customers of other wireless providers that regularly use or were roaming on AT&T’s network.
• It took AT&T at least 12 hours to fully restore service.
• The outage also cut off service to devices operated by public safety users of the First Responder Network Authority (FirstNet). AT&T prioritized the restoration of FirstNet before other services but did not notify FirstNet customers of the outage until three hours after it began, and nearly one hour after service was restored.
• The incident began after AT&T implemented a network change with an equipment configuration error. The report details numerous factors that resulted in the extensive scope and duration of the outage, and it cites the corrective actions since taken by AT&T to prevent a reoccurrence.

The FCC’s Public Safety and Homeland Security Bureau, the division that handled the investigation, has turned the matter over to the Enforcement Bureau. If the Enforcement Bureau finds that AT&T violated FCC rules, the carrier could face penalties.