At 11:20 a.m. Wednesday, you’re going to hear an alert blaring from your cellphone—and your radios and televisions, too. 

But don’t be alarmed. 

They’re just part of a test the Federal Emergency Management Agency and the Federal Communications Commission are conducting nationwide to test out the nation’s Emergency Alert System, which is broadcast on television and radio networks, and Wireless Emergency Alerts, which go straight to cellphones.

“The purpose of the Oct. 4 test is to ensure that the systems continue to be effective means of warning the public about emergencies, particularly those on the national level,” a press release posted on the FEMA website reads.

The test will be only the second ever for all consumer mobile devices. The first took place in 2021, while a preliminary test in 2018 did not reach all cellphones. This will be the seventh such emergency alert test on radios and televisions.

By law, federal officials have to conduct a nationwide test of the public alert and warning system “not less than once every three years.”

Here’s What To Expect

At 11:20 a.m., an alert will be disseminated for a half-hour to all cellphones that are turned on and not on airplane mode, within range of a cell tower and on a wireless provider that supports the national alert system.  

Along with the alarm, phones will also start vibrating. Users will receive a message on their devices: “THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.” Users with their device’s language set to Spanish will receive a translated message.

The radio and television test should be more familiar, similar to the test messages that are broadcast on television and radio monthly. Those messages will only be broadcast for a minute.