We’re only a few weeks away from a massive test of the country’s emergency broadcast system.

On Wednesday, Oct. 4 at 2:20 p.m. ET (1:20 p.m. CT), cell phones, TVs and radios across the U.S. will send an alert message to test the Emergency Alert System, or EAS, and the Wireless Emergency Alerts, or WEA. The EAS portion of the test, the seventh to be conducted nationwide, will be sent to radios and televisions. The WEA portion will be directed at cell phones, the second time all cellular devices have been included in the run-through.

According to the Federal Emergency Management Agency, the purpose of the test is to ensure that the system remains an effective means of warning the public about emergencies, particularly those on a national level.

Here’s what will happen to cell phones:

• Beginning at 2:20 p.m. ET (1:20 p.m. CT), cell towers will broadcast the test for approximately 30 minutes. During this time, wireless phone that are on, in range of an active cell tower and whose wireless carrier participates in the WEA program will receive the test message in the form of a text.
• The message will say “THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.” It will be sent in English or Spanish depending on how the phone’s main menu is set.
• Wireless phones should receive the message only once.

Here’s what to expect on TV and radio:

• The EAS portion of the test is set to last about one minutes and will be conducted via radio and television broadcasts, on cable, satellite radio and other television providers.
• The test will be similar to regular messages that are distributed each month and will say  “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.”

In the event of severe weather or other significant events, the tests will be delayed to Oct. 11.