SOS symbol appearing on iPhones during AT&T outage. What does it mean?

Cellular customers across the nation were grappling with service disruptions during a nationwide telecommunication outage Thursday morning, with customers of AT&T among those most impacted, according to Downdetector.com.

Despite the widespread outage, customers could still make emergency calls through SOS mode

As of 11:20 a.m., nearly 57,000 AT&T customers were reporting outages, Downdetector said. At peak (between 8 and 9 a.m.) nearly 74,000 customers were reporting outages.

“Some of our customers are experiencing wireless service interruptions this morning. Our network teams took immediate action and so far three-quarters of our network has been restored. We are working as quickly as possible to restore service to remaining customers,” AT&T said in an emailed statement to USA TODAY just after 11:15 a.m.

The company did not share information on what sparked the outage.

The outage also impacted services from Verizon, Cricket Wireless and T-Mobile. It also began to impact essential public services, including people’s ability to call emergency responders.

But what does the SOS symbol mean, and how does it connect to the outage? Here's what to know.

What does the SOS symbol on the iPhone mean?

During Thursday's outage, an SOS symbol appeared on the screens of iPhone users with AT&T cellular service.

The SOS symbol can appear in the status bar of iPhones and iPads, which means that the devices are no longer connected to a cellular network. It also means there is a cellular network "available for emergency calls," Apple's support website states.

The SOS feature is available on iPhones and iPads in the U.S., Australia and Canada.

"When you make a call with SOS, your iPhone automatically calls the local emergency number and shares your location information with emergency services," according to Apple. "In some countries and regions, you might need to choose the service that you need."

After making an emergency call, your iPhone alerts any emergency contacts designated in your phone.

According to Apple, all iPhone models 14 or later can also use Emergency SOS via satellite to text emergency services when no cellular and Wi-Fi coverage is available.

Includes reporting by USA Today reporters Emily DeLetter, Christopher Cann and Gabe Hauari

This article originally appeared on Rochester Democrat and Chronicle: SOS symbol appearing on iPhones during AT&T outage. What does it mean?