NORFOLK, Va. — Thousands of AT&T's cellular customers were left without service Thursday because of a massive reported outage across the U.S., leaving them unable to place calls, send texts or access the internet.
Downdetector, which tracks online outage reports submitted by users, showed more than 64,000 customers have reported issues, as of 8:30 a.m. Eastern.
The outages began at approximately 3:30 a.m. ET. The carrier has more than 240 million subscribers, the country's largest.
“Some of our customers are experiencing wireless service interruptions this morning. We are working urgently to restore service to them. We encourage the use of Wi-Fi calling until service is restored,” AT&T said in a statement.
So far, no reason has been given for the outages. But Lee McKnight, an associate professor in the iSchool at Syracuse University, believes the most likely cause of the outage is a cloud misconfiguration or human error.
"A possible but far less likely outcome is an intentional malicious hack of ATT’s network, but the diffuse pattern of outages across the country suggests something more fundamental,” McKnight said in an emailed statement.
Two sources briefed on the situation told ABC News that the FBI and DHS, among other agencies, are now urgently investigating to determine whether the AT&T outages are the result of a cyber attack, a hack or simply some sort of technical malfunction. The investigation is of the highest priority given the critical nature of the company’s operations and the fact that the FirstNet first-responder network has been affected by the outage.
The City of Virginia Beach says that the AT&T issue may impact people calling 911. They ask that people call 757-385-5000 or access the online chat portal on their website.
Currituck County also warned on Facebook that AT&T customers that they may be unable to make or receive calls, including to 911.
Cricket Wireless had more than 13,000, the outage tracking website said Thursday. Verizon had more than 4,000 outages and T-Mobile had more than 1,900 outages. Boost Mobile had about 700 outages.
Verizon and T-Mobile both said in their statements they didn't experience outages.
“Verizon’s network is operating normally. Some customers experienced issues this morning when calling or texting with customers served by another carrier. We are continuing to monitor the situation,” Verizon said.
“Our network is operating normally. Down Detector is likely reflecting challenges our customers were having attempting to connect to users on other networks,” T-Mobile said.
Customers still appear to have access to "SOS mode," which allows cell phone users without access to regular service to call 911 in an emergency, piggybacking off of other networks nearby to do so.
The outage became a major trend on social media overnight, with users on X (formerly Twitter) flocking to a number of hashtags to discuss the issue. Although #CyberAttack was one of the trending hashtags associated with the outage, there is no indication that an attack was the cause of the outage.