Verizon's cell towers are seen in this file photo. REUTERS/Bing Guan/File Photo
WASHINGTON (Reuters) -Verizon has fully restored a network disruption that impacted thousands of customers in the U.S. The Federal Communications Commission said earlier on Monday it was investigating the company's network outage across the U.S. after thousands of users reported outages.
Verizon said in a statement later on Monday that the service has returned to normal levels.
Chicago and Seattle were among the hardest-hit cities and some iPhone users were stuck in "SOS" mode.
According to the tracking website Downdetector.com, the outage began at around 9:30 a.m. ET and there were 28,842 reports as of 5:02 p.m. ET, with regions including Minneapolis, Phoenix, Omaha and Denver among the most reported areas being affected.
Verizon Communications said earlier in the day that its engineers were making progress on the network issue and service has started to be restored.
"We apologize for any inconvenience some of our customers experienced today," Verizon said, without providing further details on the reason behind the outage.
There were about 105,000 reports around 11:19 a.m. ET, at the peak of the outage, according to Downdetector.com.
The FCC said it was "working to determine the cause and extent of these service disruptions."
Some Verizon users said on social media platform X that their phones were stuck in "SOS" mode.
"SOS" appears in the status bars of iPhones if the device is not connected to a cellular network but can still make emergency calls through other carriers, according to Apple's website.
The outage tracking website also showed 448 incident reports by AT&T users as of 5:15 p.m ET, but the carrier said it was not experiencing a nationwide outage and the network was operating normally.
"Downdetector is likely reflecting challenges our customers are having attempting to connect to users on another network," AT&T said.
Sector rival AT&T faced nationwide wireless outages in February that lasted over 12 hours and impacted more than 70,000 customers.
The FCC is investigating the AT&T outage, which blocked more than 92 million voice calls and prevented more than 25,000 attempts to reach 911, the agency said.
News of the Verizon outage came hours after the company announced a deal to give infrastructure firm Vertical Bridge rights to lease, operate and manage 6,339 mobile towers across the U.S. for $3.3 billion.
(Reporting by Harshita Mary Varghese and Aditya Soni in Bengaluru and David Shepardson in Washington; Additional reporting by Gursimran Kaur, Editing by Anil D'Silva, Tasim Zahid, Devika Syamnath, Mark Porter and Alan Barona)
