https://www.cnet.com/news/at-t-fined-5-25m-over-911-outage-that-dropped-15000-calls-to-emergency-services/

When you call 911, you expect emergency services to pick up the phone. But last year, AT&T dropped some 15,000 emergency calls and failed to notify call centers quickly -- and now the company has been fined $5.25 million to settle an FCC investigation into the outages.

According to the FCC (PDF), there were actually two outages: the one in March that dropped some 12,600 calls over the course of 5 hours, and another that lasted 47 minutes and dropped 2,600 calls to 911 in May.