For the first time ever on Wednesday, nearly everyone in the United States who owns a cell phone will see their screen light up with a message from President Donald Trump. The alert is the first test of a national presidential alert system that will give any president the ability to issue a warning directly to the American people during a crisis.

The U.S. Federal Emergency Management Agency (FEMA) is coordinating the test along with the Federal Communication Commission (FCC) to conduct the nationwide test on Wednesday, Oct 3 at 2:18 p.m. ET.

A test of the presidential alert system was originally scheduled for September 20, but authorities decided to delay the alert at the time because first responders were dealing with the aftermath from Hurricane Florence.

If you’re wondering if you can block the alert, sorry for the bad news, but you can’t thanks to a 2008 law passed by Congress. Most major mobile phone carriers volunteered to partner with the FCC and FEMA to create a way for emergency messages to be sent to your phone. Presidential Alerts cannot be silenced. If you try and turn your phone off, the alert will still be waiting for you when you turn it back on if it hadn’t already expired.

If you’re in a situation where you can’t have a lot of noise, you can disable some of the alerts you get, such as Amber Alerts about missing and abducted children, however, authorities recommend against doing that.

But, if you’ve got a sleeping baby, or just appreciate the silence, you can disable the alerts fairly easily depending on the type of phone you own. For iPhone owners, go into your Settings, then Notifications and scroll to ‘Government Alerts’. That’s where you can toggle them on or off.

For those people who own an Android phone, it depends on the type of phone you have, but you can learn how to turn those off here.

If you’ve never heard your phone sound off for an emergency or Amber Alert, it’s definitely loud, annoying, and guaranteed to grab your attention.