T-Mobile, Verizon and AT&T customers were mystified on Monday when some of their calls stopped going through, in what turned out to be a nationwide outage for T-Mobile’s network, specifically, that lasted most of the day. Around 1AM Tuesday, the company tweeted that voice calls and text messaging services had been fully restored.
According to reports on Downdetector and on social media, the outage spiked around 2:20PM ET Monday. While AT&T told The Verge that its network was “operating normally” and Verizon said its network was “performing well,” T-Mobile confirmed that it was working to fix “a voice and data issue that has been affecting customers around the country.”
Verizon also said it was not to blame: “We’re aware that another carrier is having network issues. Calls to and from that carrier may receive an error message,” read part of a statement from the company. It makes sense that what appears to be a multi-network outage could actually stem from a single carrier, since people reporting failed calls don’t always know which carrier their recipient is using.
As of 6PM ET, T-Mobile had already restored data services, but was still struggling to return phone calls to normal.
As of nearly midnight ET, six hours after that update, T-Mobile wasn’t quite finished yet. “We are recovering from this now but it may still take several more hours before customer calling and texting is fully recovered,” read a blog post from T-Mobile CEO Mike Sievert.
Multiple Verge staffers were unable to place calls on T-Mobile on Monday. It appeared that both Sprint, now a T-Mobile subsidiary, and US Cellular were also experiencing problems.
It’s still unclear what the issue might have been, though T-Mobile said early Tuesday AM that it was an “IP traffic related issue that has created significant capacity issues in the network core throughout the day.” Earlier this evening, FCC chairman Ajit Pai tweeted that the outage was “unacceptable” and that the FCC will launch an investigation.
During the T-Mobile outage and a brief Facebook Messenger outage, a rumor spread on social media that the United States was suffering a massive targeted distributed denial of service (DDoS) attack, but so far those rumors seem unfounded. Security researcher Brian Krebs, who knows a thing or two about DDoS attacks, tweeted that there was no indication that the outage was related.