This is nothing new, and the system has been tested before.
The tone went off at 2:18 p.m. EDT.
"In the event of a national emergency, a Presidential WEA alert would be issued at the direction of the President and/or his/her designee, and activated by FEMA", the agency says.
Two minutes after the phone message, television and radio also conducted the emergency alert test we are familiar with in cases of severe weather. No action is needed, ' " FEMA wrote.
They do this using a system known as the Integrated Public Alert and Warning System (IPAWS).More news: Brewers beat Tigers, NL Central tiebreaker vs. Cubs looms
It's described as "a national public warning system that provides the President with the communications capability to address the nation during a national emergency".
"When those messages appear on mobile devices, people should take those extremely seriously", FEMA's Antwane Johnson told CBS News correspondent Anna Werner. Some cell phones will receive the message; others will not.
The exercise had been scheduled for September 20, but was delayed until October 3 due to the impact of Hurricane Florence in North and SC.
FEMA officials estimate almost 75 percent of all mobile phones in the country, including major carriers, will receive the alert.More news: FC Barcelona - Champions League - 3 October 2018
Comic Kathy Griffin, a longtime Trump critic, used her Twitter account to show a phony Presidential Alert reading: "FAILED COMIC KATHY GRIFFIN IS TRYING TO DESTROY A GREAT MAN, BRETT KAVANAUGH!"
Legislation about emergency alerts have been rising since 9/11.
The message went out to smartphones at 2:18pm ET Wednesday, as the US President tested how it will work in a new collaboration with the Federal Emergency Management Agency (FEMA). A similar wireless emergency alert test message has been sent to all cell phones nationwide. If you get the message, that means everything is as it should be! "No action is required". It's not supposed to be used for political purposes, and it will only be used very rarely. You can turn your phone off (and leave it off for about half an hour) if you don't want to receive the alert.
The test was mandated under a 2015 law that said one must be run at least once every three years.
When news of these presidential alerts were first publicized, meanwhile, some characterized them as a way for President Trump to send out nationwide texts to everyone as simply as he might send a tweet.More news: You wouldn’t last two weeks without us, Donald Trump tells Saudi king