Massachusetts police pleaded with people to stop flooding them with test calls. A North Carolina man said his job ground to a halt. A Virginia teacher couldn’t contact his wife about child care.
“It is halting a lot of people from doing their jobs,” Walton said Thursday, speaking on a call through his home internet connection.
The ability to call emergency services was disrupted for some people across several states — such as California, North Carolina, Virginia and Texas — prompting some 911 centers to urge AT&T customers to use a landline for any calls, or find a cellphone that uses a different carrier.
The nationwide outage, as well as the rapid spread of reports and alerts, showed how heavily the United States relies on a handful of large cellphone providers for communications, information and critical services.
The Massachusetts state police said many of the state’s emergency centers were getting calls from people trying to see if 911 works. “Please do not do this,” the Massachusetts state police said on X.
By around 3 p.m., AT&T said it had restored service to all customers. “We sincerely apologize to them,” Jim Greer, a company spokesman, said in a statement. “Keeping our customers connected remains our top priority, and we are taking steps to ensure our customers do not experience this again in the future.”
But people such as Walton, a customer service professional at a gardening tool company, endured hours of anxiety Thursday morning. Walton, speaking before his cellphone service returned, said his work had largely stopped and would probably stay that way until AT&T was back to normal.
“It’s kind of scary, because we don’t know how long this is going to be out for,” said Walton, who added that he was hunkering down at home because he feared missing texts and calls if he strayed from his WiFi network.
AT&T did not say how many customers were affected. But Ookla, operator of the DownDetector and Speedtest.net sites, received reports of problems from more than 1.7 million AT&T users as of 2 p.m., with a peak between 8:19 a.m. and 9:34 a.m.
AT&T, which had more than 71 million postpaid wireless subscribers at the end of 2023, did not say what caused the outage.
National Security Council spokesman John Kirby said the FBI and the Department of Homeland Security are looking into the outage. The Federal Communications Commission is also investigating the outage, a spokesperson said.
The absence of a possible explanation gave way to a flood of speculation about the cause — from a cyberattack to a solar flare that disrupted satellites. But some experts who study the communications industry saw an AT&T mishap as a more probable source of the outage.
“It most likely seems like a software update gone wrong,” said Northeastern University professor Josep Jornet said, adding that the update probably worked on some hardware and not others.
Though he did not explicitly rule out a cyberattack, Jornet said that the most-affected cities — Houston, Chicago and Dallas, according to reports from Ookla — seemed too random for an intentional act.
A cyber malware attack is still a possibility, New York University professor Ted Rappaport said, noting the nationwide scope of the incident. But he also said the more likely scenario was an “an inadvertent software error.”
Rappaport, like other scholars, ruled out the possibility of a solar flare, saying that such a cause would have a “blanket effect” on cell service that did not arise on Thursday.
A small number of customers from Verizon and T-Mobile reported service interruptions, but both carriers said they did not experience outages. Reports about their outages, the companies said, probably stemmed from customers being unable to contact AT&T users.
Outages on the AT&T network and its discount carrier, Cricket Wireless, began spiking in the early morning hours and quickly grew to tens of thousands of reports on DownDetector, peaking shortly after 9 a.m. Eastern time and gradually decreasing for the rest of the morning.
Jacob Saur, administrator of Arlington County Public Safety Communications and Emergency Management in Virginia, said the department stopped receiving 911 calls from AT&T users around 6:30 a.m. and started receiving calls again around 6:45 a.m. The department detected no outages from other carriers and was still able to receive emergency texts from AT&T users, he said.
After communicating with other emergency departments, the Arlington County agency determined it was an outage throughout the Washington metropolitan area, Saur said.
The city of Upper Arlington, Ohio, notified residents in a message on X that the AT&T outage was affecting some fire alarms, in which the fire department may not be notified when an alarm is activated. The city told residents to follow up any fire alarms with 911 calls.
AT&T customer Chip Chace said his cellphone had no service at 8:20 a.m. He said his cell service was off when he woke up Thursday at 6:30 a.m., with his service bars reading “SOS.”
“It’s definitely frustrating,” said Chace, a teacher from Fork Union, Va. “My wife works in D.C. during the week, so not being able to use my phone to talk to her in the morning while I take our son to day care is not ideal.”
For Chace, who spoke to The Washington Post via direct messages on X, the outage highlighted the central role of cellphones in the modern world: “It’s concerning because you don’t realize how important your cellphone is until you can’t use it.”
Shira Ovide and Jason Samenow contributed to this report.
