FCC calls hours-long T-Mobile service outage ‘unacceptable’

NEW YORK -- The head of the U.S. communications regulator said T-Mobile’s nationwide, hours-long outage Monday was “unacceptable” and that the Federal Communications Commission will investigate.

T-Mobile, one of the country’s three largest cellphone service providers, said it had a “voice and text wireless issue” that began around noon EDT Monday. The company said at 1 a.m. Tuesday that all problems had been resolved.

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.

On Tuesday, T-Mobile's President of Technology, Neville Ray, released a new statement about the recent outage and issues for voice and text message, or VoLTE (Voice over LTE) capabilities for Sprint customers.

Ray said the outage was a "trigger event", or fiber circuit failure, caused by a third-party provider outage in the Southeast. The overload, Ray said, caused a "IP traffic storm", affecting all IMS (IP multimedia Subsystems) and VoLTE calls.

Ray said hundreds of engineers worked to fix the outage, and data connects and non-VoLTE programs--such as  services FaceTime, iMessage, Google Meet, Google Duo, Zoom, Skype-- continued to function for T-Mobile customers by 10 p.m. PDT Monday. T-Mobile said they are working to add "permanent additional safeguards" to ensure the issue doesn't reoccur in the future.

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.