The company blamed an internet-traffic issue that caused problems with its network for the outage. AT&T and Verizon both said their networks were operating normally. But calls between their customers and T-Mobile customers could have run into trouble because of T-Mobile’s issues, creating the impression of a widespread communications failure.
The FCC has fined telecom companies in the past for network outages. T-Mobile paid a $17.5 million fine for two nationwide service outages on the same day in August 2014, which together lasted three hours and prevented customers from being able to call 911.
Public-safety officials were worried about lack of access to 911 on Monday as well. For example, the Redmond, Washington, police department tweeted that T-Mobile customers should have “an alternate plan in place in the event you need to call 911.”
T-Mobile, which is based in Bellevue, Washington, became one of the country’s largest carriers, along with AT&T and Verizon, after buying rival Sprint. The company has started integrating the two networks.