A cellular outage early on Thursday hit thousands of AT&T users in the United States, disrupting calls, text messages and emergency services in major cities.
Cellular outage in U.S. hits AT&T, T Mobile and Verizon users, Downdetector shows::undefined
Wait - the article you linked clearly says AT&T only, not other services. It also sites an AT&T spokesperson blaming a software upgrade on their network as the cause. So any other outages at other providers would be completely coincidental.