Here's why your phone will go berserk this afternoon

75 percent of all wireless users to get nationwide alert, officials say

WASHINGTON – About 225 million mobile devices across the U.S. will receive a test emergency alert Wednesday.

It's the first nationwide test for a wireless phone emergency alert. It will be sent at 2:18 p.m. Eastern time, according to the Associated Press.

The Federal Emergency Management Agency says it'll sound like an Amber Alert or flood warning. The subject will read: "Presidential Alert." The text will say: "THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed."

It's not a political message but an emergency test message sent from President Donald Trump as part of FEMA's system to warn the public in cases of national emergencies, according to CNN.

WEA was technically launched in April 2012, but this will be the first time FEMA has tested the system on the presidential level in hopes to work out the kinks, the agency said in a press release last month.

The presidential alert is one of three kinds of alerts in the FEMA's WEA system, which also notifies the public about extreme weather or missing children, also known as Amber Alerts.

You can expect to see the alert pop up on your phone so long as you have it turned on, are within range of a cell tower, and your wireless provider is part of the WEA system.

More than 100 carriers, including the largest carriers, such as Verizon, AT&T, Sprint and T-Mobile, will participate in the emergency alert test, FEMA said.

FEMA officials say the test will last about a half-hour, so some people may get it at different times. They expect about 75 percent of all wireless users to get the alert. Users can't opt out of the presidential alert test, according to FEMA.

The alert would be used in the event of a major nationwide emergency.

FEMA will also run a test of its Emergency Alert System for radio and television broadcasters Wednesday, beginning two minutes after the WEA test.

The agency is required by law to conduct a nationwide test of its public alert systems no less than once every three years.

FEMA is also tasked with ensuring that the President can alert the public under all conditions in cases of national emergencies, including natural disasters and terrorist threats.

To find out more about who can send the WEA messages and when you might see them, read the infographic from FEMA below.