From CONELRAD in the Cold War days to the EBS in the 70s and 80s, that familiar "this is only a test" line has become part of American culture - almost as much as the smartphones we now get those tests and alerts on.

"EAS is a tried and true and trusted method of sending out emergency alerts in a blast format," says Brian Castner, spokesman for the Ohio Emergency Management Agency. 

Wednesday marked the latest effort by the Federal Emergency Management Agency and the Federal Communications Commission to test the Emergency Alert System and its Wireless Emergency Alert capabilities.
Like the tests we grew up hearing, this one was just a way for public safety officials to make sure critical information gets to you as fast as possible during a crisis.
"If you send out an EAS message over TV and radio, everyone gets the same message at the same time," said Castner. "If a message goes out over social media for example, the response time and reception time may be different."
But unlike prior national tests, this one didn't trigger everyone's phones.
Turns out Washington didn't want to overwhelm the tens of millions of American cellular customers.
"So we were asked to coordinate at the state level requesting participants like broadcasters, 911 administrators, emergency officials to participate," explained Castner.
A recent EAS change has come from the National Weather Service. There are now tiered criteria for severe thunderstorm warnings, and if the Weather Service deems a severe thunderstorm "destructive", it will trigger a Wireless Emergency Alert on your phone if you have them switched on.
The EAS will continue to be used for AMBER Alerts, too, and if there's ever a national disaster or crisis that impacts travel routes or the supply chain, the EAS will make sure you hear about it.