WASHINGTON—T-Mobile USA agreed to settle a U.S. probe for $19.5 million after a massive 2020 outage led to more than 20,000 failed 911 emergency calls. The settlement was prompted by a Federal Communications Commission investigation into a more than 12-hour outage in June 2020 that led to congestion across No. 3 wireless carrier T-Mobile’s networks, and caused “the complete failure of more than 23,000 911 calls.” T-Mobile as part of the consent decree with the FCC has also agreed to make new commitments to improve 911 outage notices. An October 2020 FCC report found the T-Mobile outage disrupted calling and texting services nationwide and access to data service in some areas. It resulted in at least 250 million total calls failing. The FCC estimated “over 250 million calls … from other service providers’ subscribers to T-Mobile subscribers failed due to the outage” and “at least 41% of all calls that …