Your phone will blare a national emergency alert test on October 4 at 2:20PM ET

The federal government will conduct a nationwide alert test on Wednesday, October 4. The Federal Emergency Management Agency (FEMA) and the Federal Communications Commission (FCC) will send notifications to cell phones (as well as radios and TVs) to test the National Wireless Emergency Alert System and ensure the system (including the public’s familiarity with it) is ready for a real crisis.

The cellphone portion of the test will assess Wireless Emergency Alerts (WEAs) nationwide. If you live near a decent-sized metro area, there’s a solid chance you’ve received AMBER alerts through this system before; it can also broadcast signals for imminent threats, public safety and presidential notices in a national emergency. The test’s WEA portion will use FEMA’s Integrated Public Alert and Warning System (IPAWS), a centralized internet-based system that can broadcast emergency notifications through various communications networks.

If your cell phone is set to English, you’ll receive a message at around 2:20PM ET reading, “THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.” Those with phones set to Spanish as their primary language will see, “ESTA ES UNA PRUEBA del Sistema Nacional de Alerta de Emergencia. No se necesita acción.”

Of course, the messages will be accompanied by a “unique tone and vibration.” Based on past tests we’ve received, that could easily be described as “a jarring and obnoxious alarm that will immediately make you stop what you’re doing, utter select obscenities and pick up your phone to make it stop.”

Using the Emergency Alert System (EAS), the television and radio portion of the assessment is scheduled to happen simultaneously. This will be the seventh nationwide EAS test.

The cell phone part of the test is scheduled to last for about 30 minutes, but you should be able to dismiss the notification and shut up your phone as soon as you see and hear it. And in the (extremely unlikely) event of an actual emergency on Wednesday, the test will take place a week later on the backup date of October 11.