A lot of Americans are going to be looking at their phones at the EXACT SAME MOMENT today at 2:20 P.M. Eastern, 1:20 P.M. CST, & 11:20 A.M. Pacific. And no, it isn't because we're ALWAYS looking at our phones anyway.
Earlier this year, the government announced that it had picked this day for a nationwide test of its Emergency Alert System and Wireless Emergency Alerts.
An alert will be sent to all radios and televisions, as well as all consumer cellphones. You don't need to do anything just ignore it. It's just like those "tests of the emergency broadcast system" that happened ALL THE TIME throughout the '80s and '90s.
The purpose is to make sure the system works, because when there's an ACTUAL emergency, like a tornado, there's no time for troubleshooting. It'll be a brief interruption but we'll ALL be dealing with it.