Verizon Communications’ mobile network was offline for thousands of users in the United States on Monday, according to outage tracking website Downdetector.com.

There were more than 100,000 incidents of people reporting problems with the telecom operator’s services, according to Downdetector, which tracks outages by collecting status reports from a number of sources, including user-submitted errors on its platform.

The outages, which started around 8:30 a.m. Dallas time, were reported from locations including Chicago, Indianapolis and Minneapolis, Downdetector said.

Some Verizon users said on social media platform X that their phones were stuck in “SOS” mode.

According to Apple’s website, “SOS” appears in the status bars of iPhones when the device is not connected to a cellular network but can make emergency calls through other carriers.

Verizon did not immediately respond to a request for comment.