More than 50,000 incidents reported in the early hours of the morning, affecting emergency services.
AT&T, the largest US mobile phone company, was reported to be the worst affected early on Thursday.
More than 50,000 incidents were reported about 7am East Coast time (12:00 GMT), according to data from the outage tracking website Downdetector.com
The website showed that the impacted cities included San Francisco, Houston, Chicago, Los Angeles, New York and Boston.
AT&T has acknowledged that some customers were experiencing wireless service interruptions. TMobile said it did not experience an outage and that its network was operating normally, but its users did report problems.
On X, the San Francisco Fire Department said the outage impacted people’s ability to reach emergency services.
“We are aware of an issue impacting AT&T wireless customers from making and receiving any phone calls,” including the 911 emergency number, the department said.
It added that it was “actively engaged and monitoring this”.
The Flagler County Sheriff’s Office in Florida also tweeted: “Texts to 911 from affected AT&T users are now being received. If you have an emergency and cannot dial out, send a text message to 911.”
UPDATE: Texts to 911 from affected AT&T users are now being received. If you have an emergency, and cannot dial out, send a text message to 911. pic.twitter.com/VKabmSfyYx
— Flagler County Sheriff’s Office (@FlaglerSheriff) February 22, 2024
North Carolina’s Charlotte-Mecklenburg Police Department also said it was aware of the outage but there were “no disruptions” to its ability to receive emergency calls.
Several users took to X to complain about the service outage with some AT&T users reporting that their iPhones were stuck in SOS mode due to the loss of connection.
“The #attoutage is affecting people’s livelihood. My dad drives Uber and can’t make a living until his cell service is working. Are you going to be refunding people @ATT ?” one user wrote.
Others questioned whether the outage was due to missed phone bill payments.