The nationwide AT&T outage that affected tens of thousands of customers Thursday has been resolved.
Wireless service was restored by afternoon, and the company said that after an initial review of the day, it believes the outage “was caused by the application and execution of an incorrect process used as we were expanding our network, not a cyber attack.”
A look at how the day unfolded.
By 4 a.m. ET, more than 32,000 AT&T customers had reported outages. The number dipped before spiking again to more than 50,000 outages around 7 a.m. In the next hour, the number again climbed to 71,000.
Customers of Verizon and T-Mobile also reported outages, but both companies said that they had not suffered an outage directly, but that customers could have had issues trying to connect with those using another carrier.
Prepaid wireless service provider Cricket Wireless, which is owned by AT&T and uses its networks, also experienced outages Thursday morning, with more than 13,500 customers reporting outages around 8 a.m.
The Federal Communications Commission is actively investigating the incident with The Federal Bureau of Investigation and Department of Homeland Security lending a hand.
Wireless service to all affected AT&T customers was restored by about 3 p.m., according to a statement from the company.
AT&T: 'We have restored wireless service to all our affected customers'
Service is back for all AT&T customers affected by today's outage.
"We have restored wireless service to all our affected customers. We sincerely apologize to them. 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," the company said in a statement.
By the numbers: Outages by carrier as of 3 p.m.
Most outages appeared to be resolved by the afternoon, according to Downdetector data.
AT&T: 3,600
Cricket Wireless: 600
Verizon: 850
T-Mobile: 500
Boost: 60
UScellular: 100
White House: FBI, DHS assisting with outage investigation
In today's White House news conference, John Kirby, the assistant to the secretary of defense for public affairs, told reporters that the FBI and Department of Homeland Security were assisting the Federal Communications Commission with its investigation into what caused today's outage.
Kirby said the FBI and DHS "are working with the tech industry (and) these network providers to see what we can do from a federal perspective to lend (a) hand to their investigative efforts to figure out what happened here."
Kirby added that there were not yet firm answers as to the outage's origins.
"This just happened earlier today," he said. "And so we’re working very hard to see if we can get to the ground truth and exactly what happened."
"I know folks in (the) industry are working hard to get restoration of services to those that are still without those services," Kirby said.
FCC is investigating AT&T outage
The Federal Communications Commission says it is actively investigating the AT&T outage.
"We are aware of the reported wireless outages, and our Public Safety and Homeland Security Bureau is actively investigating. We are in touch with AT&T and public safety authorities, including FirstNet, as well as other providers," said the FCC, which oversees communication by radio, wire, satellite and cable across the country.
The U.S. Cybersecurity and Infrastructure Security Agency is also monitoring the situation.
How to use your iPhone in ‘SOS mode’ amid AT&T outage
While AT&T works to figure out what caused the outage for customers in major cities, users are resorting to using “SOS mode,” which enables emergency services and shares your location.
NBC’s Brian Cheung reports that emergency services is calling on users not to call 911 to test if phones are connected to the network.
Professor believes 'cloud misconfiguration' is likely cause of outage
AT&T has not said what caused today's nationwide outage.
However, Lee McKnight, an associate professor at Syracuse University’s School of Information Studies, said the most likely cause “is a cloud misconfiguration. Which is a fancy word for saying 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,” he added in a statement.
By the numbers: Outages by carrier as of 1 p.m.
Outages have declined steadily today.
Here are the latest numbers, according to Downdetector.
AT&T: 16,700
Cricket Wireless: 3,100
Verizon: 1,300
T-Mobile: 800
Boost: 270
UScellular: 130
Agencies give guidance on what to do in case of an emergency
Agencies across the country urged for calm amid AT&T's outage, some acknowledging that customers were briefly unable to contact 911.
Multiple agencies including the San Francisco Fire Department, Texas’ Fort Worth police, Chicago’s Office of Emergency Management and Communications, Virginia’s Prince William County Police Department, and North Carolina’s Charlotte-Mecklenburg Police Department stressed that their 911 call centers were operational.
“If you are an AT&T customer and cannot get through to 911, then please try calling from a landline. If that is not an option then please try to get ahold of a friend or family member who is a customer of a different carrier and ask them to call 911 on your behalf,” the San Francisco Fire Department said on X, a messaged echoed by other agencies.
Maryland's Montgomery County Department of Police asked people to refrain from calling 911 to test their cellphones.
"Please only dial 911 for an actual emergency," the department said.
Agency tasked with monitoring cyber threats is monitoring the situation
The U.S. Cybersecurity and Infrastructure Security Agency said it is in touch with AT&T but did not say there is any indication of a cyberattack.
“CISA is aware of the reports and we are working closely with AT&T to understand the cause of the outage and its impacts, and stand ready to offer any assistance needed,” Eric Goldstein, the agency’s executive assistant director for cybersecurity, said in an emailed statement.
75% of AT&T's network has been restored, company says
AT&T is making progress in restoring service to tens of thousands of customers affected by this morning's nationwide outage.
"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," the company said in a statement.
Cricket Wireless later issued an identical statement.