WASHINGTON (AP) — Wireless carrier T-Mobile agreed to pay $19.5 million in a settlement with the Federal Communications Commission over a 12-hour nationwide outage in June 2020 that resulted in thousands of failed 911 calls.

The FCC said Tuesday that as part of the settlement, T-Mobile will also commit to improving communications of outages to emergency call centers, among other measures.

The agency said there was a “complete failure” of more than 23,000 911 calls because of the outage. There were also calls that did go through but without key information, like a callback number or location data.

The FCC's investigation said the outage began because of a failure in part of T-Mobile's network, which was made worse by routing and software errors.

The Bellevue, Washington, company said that the June 2020 episode was a “short-term isolated outage and we immediately took steps to further enhance our network to prevent this type of event from happening in the future.”

This is not the first time such outages have happened. T-Mobile paid a $17.5 million fine after two related nationwide service outages on the same day in August 2014.