About 225 million mobile devices across the U.S. will receive a test emergency alert on Wednesday. It’s the first nationwide test for a wireless phone emergency alert. It will be sent at 2:18 p.m. EDT. The Federal Emergency Management Agency said that it will 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.” A test of broadcast systems will happen at 2:20 p.m. EDT. FEMA officials say the test will last about a half-hour; meaning people may get it at different times. They expect about 75% of all wireless users to get the alert. The alert would be used in the event of a major nationwide emergency.