More than 95,000 cases of Verizon outages were reported across the country, according to the website Downdetector.
Thousands of Verizon users across the United States reported having no cellphone service on Monday morning in major cities, including in Atlanta, Chicago, Denver, New York and Phoenix.
According to the website Downdetector, which tracks user reports of internet disruptions, more than 95,000 cases of Verizon outages were reported across the country as of 11:15 a.m. Eastern, more than an hour after the first issues were reported.
A map posted on the site showed cities with the most reports.
On the site, users said their cellphones were intermittently displaying "SOS" mode and that they could not place calls or send or receive text messages.
Verizon did not immediately respond to a request for information.
On social media, where many users went to check if outages were widespread, Verizon technical support was only responding individually to scores of users reporting the "SOS" problem on Monday morning.
Verizon, one of the largest cellphone carriers in the world, has 114.2 million wireless subscribers in the United States.
This is a developing story.