CNN
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AT&T's network was down Thursday morning for many of its customers across the United States, leaving customers unable to make calls, send text messages or access the Internet.
While Verizon and T-Mobile customers reported some network outages, they were relatively rare. T-Mobile and Verizon said their networks were not affected by AT&T's service outage, and that customers reporting the outage may not be able to reach customers using AT&T.
What can you do if you don't have service?
If you're an AT&T customer, you can enable Wi-Fi calling without phone, text, or Internet access. If you have Wi-Fi access, you can call and send texts.
More than 73,000 AT&T customers have reported outages on a digital-service monitoring site Downdetector. This is not a comprehensive number: it only tracks self-reported outages. While outage reports dropped slightly at 5 a.m. ET, they rebounded at 7 a.m. ET.
AT&T acknowledged the widespread outage, but did not provide a reason for the system failure.
“Some of our customers are experiencing wireless service interruptions this morning. We are working urgently to restore service to them,” AT&T said in a statement. “We encourage you to use Wi-Fi Calling until service is restored.”
The company said parts of its network had begun to recover, but there was no timeline for when its system would be fully restored. AT&T responds to customer complaints online and requests direct messages to customer service.
Why AT&T Collapsed
AT&T has experienced sporadic outages over the past few days, including a temporary 911 outage in parts of the southeastern United States. Although outages do occur from time to time, across the country, sustained outages are extremely rare.
While AT&T did not provide an official cause for the outage, it appears to be related to how cellular services route calls from one network to another, a process known as peering, according to an industry source who spoke on condition of anonymity.
An industry source said there was no indication that Thursday's outage was the result of a cyber attack or other malicious activity.
Many local governments said AT&T's outage would disrupt its services.
San Francisco Department of Emergency Management a Report on X Its 911 center remained operational Thursday morning, but many AT&T customers were unable to reach emergency service because of the outage. It suggested people call from a landline or find someone with a competitor's service to dial 911.
“We are aware of an issue that affects AT&T Wireless customers from making and receiving any phone calls (including 911),” the department said in its filing. “We are actively monitoring this.”
The fire department in Upper Arlington, Ohio, said the AT&T outage was affecting its fire alarms. St. Joseph County, Michigan advised residents to use Wi-Fi to make 911 calls if they cannot reach 911 on AT&T's network. Cobb County, Georgia, said its 911 operations were not affected by the outage, but customers may want to find alternative methods of reaching emergency services. Cabell County, West Virginia, said customers who cannot reach 911 can text 911 as a last resort.
Officials with the New York Police Department told CNN Thursday morning that AT&T phones could not make calls or use emails unless they were connected to Wi-Fi.
Verizon and T-Mobile say they are not affected
About 1,000 outages were reported by Verizon and T-Mobile customers Thursday morning, according to the Town Detector website.
“We did not experience an outage,” T-Mobile said in a statement. “Our network is operating normally.”
Verizon made a similar point, saying it was not affected by AT&T's outage.
“Verizon's network is operating normally,” Verizon told CNN in a statement. “This morning some customers experienced issues calling or texting customers served by another carrier. We are continuously monitoring the situation,” he said.
The company added that user reports on Downdetector about T-Mobile outages “reflect the challenges our customers are having trying to connect to users on other networks.”
Downdetector, the website says, “provides real-time status information for more than 12,000 services at 47 sites representing 47 countries.”
This is a developing story and will be updated.
CNN's Carol Alvarado and John Miller contributed to this report.