A nationwide cell phone outage hit thousands of AT&T users on Thursday morning.

📱 What’s happening

More than 70,000 AT&T outages were reported after 8 a.m. ET, according to Downdetector, a website that detects outages. The first outages were reported just before 4 a.m.

“Some of our customers are experiencing wireless service interruptions this morning,” AT&T said in a statement to the Associated Press. “We are working urgently to restore service to them. We encourage the use of Wi-Fi calling until service is restored.”

AT&T, the nation’s largest carrier, has more than 240 million subscribers. No reason has been given for the outages.

🆘 Phones switched to SOS mode

Scores of AT&T users reported their phones were switched to “SOS” mode. For Apple’s iPhones, “SOS” mode appears when your device isn’t connected to a cellular network. But you can still make emergency calls. The feature is available in the United States, Canada and Australia.

➡️ What other cell phone customers were affected?

Cricket Wireless had more than 13,000 outages, according to Downdetector. Verizon had more than 4,000 outages; T-Mobile had more than 1,900 outages; and Boost Mobile had about 700 outages.

But both Verizon and T-Mobile said that its networks were operating normally and that the outages listed on Downdetector were likely a result of their customers calling or texting with AT&T subscribers.

“Our network is operating normally,” T-Mobile said in a statement to the AP. “Down Detector is likely reflecting challenges our customers were having attempting to connect to users on other networks.”

🚑 Emergency services affected

In San Francisco, the outage was impacting people’s ability to reach emergency services by dialing 911, according to a post on X by the city’s fire department.

“We are aware of an issue impacting AT&T wireless customers from making and receiving any phone calls (including to 911),” the San Francisco Fire Department said. “We are actively engaged and monitoring this.

“The San Francisco 911 center is still operational,” it added. “If you are an AT&T customer and cannot get through to 911, then please try calling from a landline. If that is not an option then please try to get ahold of a friend or family member who is a customer of a different carrier and ask them to call 911 on your behalf. Do not call or text 911 to simply test your phone service.”