Today is the day for the US government's big emergency alert drill, which will send a test message to every TV, radio and cell phone in the nation.

Starting at approximately 2:20 pm ET on Wednesday, the federal government will begin conducting a nationwide test of its Emergency Alert System and Wireless Emergency Alerts. The EAS portion of the test will send an emergency alert to all radios and televisions, while the WEA portion of the drill will send an alert to all consumer cell phones.

The test is being conducted by the Federal Emergency Management Agency in coordination with the Federal Communication Commission. Its purpose is to ensure that the systems in place continue to be an effective means of warning the public about emergencies at a national level.

Essentially, what this means is that you can expect hundreds of millions of cell phones around the country to make a screeching alert noise at approximately the same time today, beginning around 2:20 pm ET. Radio and TV stations will also blare a test alert at around the same time. But there is no action required from you after receiving the free message — it is just a test.

Here are answers to all of your burning questions about today's emergency alert test.

Can I opt-out of this test on my cell phone?

While some recent models of mobile phones may include a setting to opt-out of tests and alerts, none of these settings will affect the 2023 national test, FEMA has said.

That means if your mobile phone is on and receiving service from a participating wireless provider, you will likely receive the national Wireless Emergency Alert test, the agency added.

There are, however, three conditions which would prevent the cell phone alert from getting delivered to a device. If your phone is turned off, has airplane mode switched on, or is not connected or associated with a cell tower, then it will not receive the message.

What if I have a phone that I am trying to keep secret?

Survivors of domestic violence and people in abusive relationships often have a secret or emergency phone that they don't want their partner or others to know about. On a call with reporters Tuesday, a senior FEMA official said the agency was aware of these concerns stemming from survivors of domestic violence and their allies. The official recommended that people who do not want a secret phone to be revealed to turn their phone completely off ahead of the 2:20 pm ET test — and not to turn it back on for thirty minutes, or until after 2:50 pm ET.

If you want to be overly cautious, you can also wait until you are in a safe place before turning your phone back on.

Won't this disrupt schools?

Educators should brace themselves for some disruption this afternoon, as the test impacting cell phones will occur during school hours for most of the country.

On the call with reporters, the senior FEMA official recommended that educators, as much as possible, try to use this as a teaching opportunity about federal emergency management and preparedness initiatives.

Will this impact my privacy?

The national test cannot be used to monitor, locate or lock your phone, FEMA has said. The test is also using broadcast technology and does not collect any of your data.

What will the alert say?

All cell 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 free text message will be sent in either English or Spanish, depending on the language settings of your device. 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 has said.

The test will be broadcast by cell towers for approximately 30 minutes beginning at 2:20 pm ET, FEMA said. During this time, all compatible wireless phones that are switched on, within range of an active cell tower, and whose wireless providers participates in WEA tests should receive the text message.

Although the test will be transmitting for approximately 30 minutes, you should only receive the alert message once.

Meanwhile, all radios and televisions will also broadcast a test emergency alert at the same time as part of the broader test. This message, which will run for approximately one minute, will state: "This is a nationwide test of the Emergency Alert System, issued by the Federal Emergency Management Agency, covering the United States from 14:20 to 14:50 hours ET. This is only a test. No action is required by the public."

Can the emergency alert impact my body?

In short: No. There are a number of false claims circulating online with regard to the test alert, including some conspiracy theories that incorrectly allege the sound emitted as part of the national test can impact your body at the cellular level. This is false.

"FEMA is not aware of any adverse health effects caused by the audio signal," the agency has stated.

And while this is a national test, it uses the same technology and infrastructure that state and local authorities rely on to send localized Amber Alerts or extreme weather warnings, a senior FEMA official emphasized to reporters on Tuesday. In a frequently asked question sheet released by FEMA ahead of Wednesday's test, the agency stated: "The audio signal that will be used in the National Test is the same combination of audio tones that has been used since 1963 in the original Emergency Broadcast System."

Why didn't I receive an emergency alert on my phone?

If you have a mobile phone that was switched on, not on airplane mode, within range of an active cell tower and on a network where wireless providers participate in Wireless Emergency Alerts then you should have received the test message on Wednesday afternoon by 2:50 pm ET.

If you are trying to figure out why you did not receive an alert when you should have, or have any other feedback on the test, members of the public can write to the email address: FEMA-National-Test@fema.dhs.gov.