T-Mobile users across the United States reported network outages late on Monday, according to an outage tracking website.

T-Mobile said it was quickly addressing a disruption that had affected some cellular services.

The U.S. wireless carrier said it was working on resolving a problem that had caused intermittent issues with voice, messaging, and data services in several areas. T-Mobile US did not say how many users had been affected.

The number of reports of T-mobile outages over the preceding 24 hours had peaked at more than 83,000 at around 10:20 p.m. ET (0320 GMT), said Downdetector.com, which tracks outages by collating status reports from sources including user-submitted errors on its platform. The number had fallen to about 9,000 by midnight ET.

T-Mobile’s help page responded to Twitter messages from users experiencing problems, saying it would review the complaints. It provided no details on the extent of or reason for the outage.

“Our teams are addressing a 3rd party fiber interruption issue that has intermittently impacted some voice, messaging and data services in several areas,” T-Mobile’s President of Technology Neville Ray said on Twitter.

Downdetector also reported thousands of reports of services of other U.S. wireless carriers Verizon and AT&T being down. The website showed more than 2,000 unresolved incident reports for Verizon and more than 1,200 for AT&T at the peaks.