U.S. phone giant AT&T confirmed Friday it will begin notifying millions of consumers about a fresh data breach that allowed cybercriminals to steal the phone records of “nearly all” of its customers, a company spokesperson told TechCrunch.

In a statement, AT&T said that the stolen data contains phone numbers of both cellular and landline customers, as well as AT&T records of calls and text messages — such as who contacted who by phone or text — during a six-month period between May 1, 2022 and October 31, 2022. 

A data set containing the personal information, including social security numbers, of 73 million current and former AT&T customers was released on the dark web, the telecommunications giant said on Saturday.

The data set hit the dark web about two weeks ago. It’s not clear whether its release came from AT&T itself, which is the world’s fourth-largest telecommunication company, or one of its vendors.

AT&T said the network disruption that caused tens of thousands of customers to lose cellular service Thursday was not the result of a cyberattack.

After service was fully restored at around 6 p.m. ET, the mobile phone service provider revealed the results of its initial investigation into the outage.

"Based on our initial review, we believe the outage was caused by the application & execution of an incorrect process used as we were expanding our network, not a cyberattack," AT&T posted on X. 

AT&T says Thursday's outage which left thousands of customers without service and unable to call 911, was "not a cyber attack," the company believes.

Why it matters: Despite threats from nation-state hackers in China and Russia, it's still statistically more likely that a network outage would be caused by misconfigurations or faulty settings.

The FCC, DHS and the FBI were reportedly all investigating the incident on Thursday, which may have led people to assume it was a cyberattack.

Last week, I was on a call with a carrier's support line trying to return my new iPhone I'd bought through its store, which meant transferring service to a backup phone. Unfortunately, I'd left that backup phone at my parents' house across town -- so when the carrier cut service and the call went dead, I had to drive half an hour to get my backup handset. 

Customers of AT&T, the country’s largest wireless provider, reported widespread outages on Thursday.

Some AT&T customers saw SOS messages displayed in the status bar on their cellphones. The message indicates that the device is having trouble connecting to their cellular provider’s network.

That can be a big problem in an emergency. AT&T urged customers to connect to Wi-Fi to use their phones.

Wi-Fi calling is a built-in feature on most Android devices and iPhones and can be turned on under the phone’s settings.

AT&T said Thursday it is working to restore service to wireless customers after people across the U.S. reported problems with making cell phone calls. 

Customers of the telecommunications giant began reporting problems on Downdetector, which tracks internet outages, after 3 a.m. ET. There were nearly 75,000 reports of outages around 9:15 a.m.

Cricket Wireless, which is owned by AT&T, also experienced network issues, with about 13,000 outages reported on Downdetector as of 9 a.m.

Tens of thousands of AT&T customers have been reporting outages this morning for their home phone, internet and mobile phone services, according to Downdetector.

The outages started popping up just before 3:30 a.m. ET, according to a graph shown on the website that tracks outages. As of 11:15 a.m. ET, the number of reports has declined to nearly 59,000 after spiking at more than 74,000 just after 9 a.m. ET.  

Thousands of Americans reported issues with their phone service Thursday morning, though it appears to be hitting AT&T customers the hardest.

According to Downdetector, more than 49,000 AT&T users reported an outage as of 7:20 a.m. ET. That’s up more than 50% from when the spike in reports began around 4:30 a.m. Around 2,900 Verizon and 1,200 T-Mobile customers also reported problems.

AT&T stock closed at its lowest price in 30 years on July 17 following a series of downgrades in the aftermath of a Wall Street Journal investigation into toxic lead cables.