Here’s what you need to know about the nationwide emergency alert on Oct. 4

Don’t be alarmed if your phone starts sounding off tomorrow, Oct. 4, around 2:20 p.m. ET—because it’s happening to everyone’s phone, television, and radio at the same time. The federal government says it will conduct a nationwide test of its Emergency Alert System and Wireless Emergency Alerts on Wednesday.

“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,” the Federal Emergency Management Agency, which is conducting the test in coordination with the Federal Communication Commission, said in a statement.

What is an emergency alert and why are we receiving it?

Emergency alert messages are divided into two groups: the Emergency Alert System (EAS) for radios and televisions, and the Wireless Emergency Alerts (WEA) for wireless phones. Both EAS and WEA alerts are scheduled to happen at the same time. The Federal Emergency Management Agency will conduct Wednesday’s test in coordination with the Federal Communications Commission, and the EAS portion of the test will sound off on all radios and televisions, while the WEA portion of the test will alert all cell phones.

Wednesday’s emergency alert will mark the seventh nationwide test of the Emergency Alert System.

“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,” FEMA’s statement states. “In case the Oct. 4 test is postponed due to widespread severe weather or other significant events, the back-up testing date is Oct. 11. “

So, what will it say? According to FEMA, on or around 2:20 pm ET this Wednesday, all wireless phones should receive an alert and an accompanying text message that reads: “THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.”

The text will be accompanied by a unique tone and vibration that is meant to make the alert accessible to the entire public, including people with disabilities, FEMA said. It’ll also be broadcast in either English or Spanish, depending on your phone’s language settings.

All compatible wireless phones that are switched on, within range of an active cell tower, and whose wireless providers participate in WEA tests should receive the text message.

“The idea is that all of these systems are trying to work together to get information out, in as many ways as possible, to the right people,” Joseph Trainor, a core faculty member at the University of Delaware’s Disaster Research Center, who studies the design of disaster warning systems and how they operate, tells CBS News. “So that folks have the information to make good choices about the risks around them.”

“When your cellphone makes a noise, you look,” he said.

What you can do if the emergency alert happens in front of your kids

You can explain to them that the noise they’re hearing is perfectly OK, and that everyone is getting the same noisy alert on their phone at the same time. Trainor tells CBS News that a good way to frame it is to focus on the facts: emergency alert tests can help prepare us to act quickly when there’s a real emergency.

“Warning systems and alert systems, they get you started,” he said. “But there’s a human decision process and, if it’s the first time you’ve ever seen one in a real event, it’s going to take you longer to make sense of what it is, and get the information you need, and process it to be able to make decisions.”