The massive cellphone outage that affected more than 1.7 million customers and disrupted 911 services in several states was not caused by a cyberattack but by an error made while AT&T was expanding its network, the company said late Thursday.
Spokesman Jim Greer said AT&T would continue to assess the outage, which began spiking early Thursday and quickly grew to tens of thousands of reports on the outage-tracking website Downdetector, peaking shortly after 9 a.m. Eastern time. He said service was restored to all customers by about 3 p.m.
“Based on our initial review, we believe that [Thursday’s] outage was caused by the application and execution of an incorrect process used as we were expanding our network, not a cyberattack,” Greer said in an email.
Still, the incident prompted at least three federal agencies, including the FBI, to investigate, authorities said.
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It’s unclear how many of AT&T’s roughly 71 million postpaid wireless customers were affected. The network intelligence firm Ookla, which runs Downdetector, counted about 1.7 million unique customers. But that number is far from complete as it relies only on self-reported outages.
Greer, the AT&T spokesman, said the company “sincerely apologize[s]” for the outage, adding: “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.”
Share this articleShareCustomers from several other carriers, including Verizon and T-Mobile, reported a smaller number of outages. Representatives of those companies said their networks were not affected and that reported outages may have come from people who tried to call AT&T customers. Cricket Wireless, a budget carrier owned by AT&T, had more than 12,000 reported outages at one point Thursday.
The outages prompted wide concern, particularly over the loss of emergency services — with some 911 centers in California, North Carolina, Texas and elsewhere urging customers to use a landline for any calls, or find a cellphone that uses a different carrier. And it underscored the influence that a handful of large cellphone carriers hold over Americans’ everyday communications and access to lifesaving services.
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On Thursday, state police in Massachusetts said 911 centers were being flooded with “test” calls, while officials in one Ohio town said the outage also affected fire alarms. One West Virginia county encouraged residents to text 911 as a last resort.
The incident also prompted a flood of speculation over the cause, though experts early on were leaning toward a technical error as opposed to a cyberattack, solar flare or other cause.
“It most likely seems like a software update gone wrong,” Northeastern University professor Josep Jornet said Thursday.
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, a spokesperson said.
Julian Mark contributed to this report.
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