Cell phones, TVs and radios across the U.S. are set to go off at the same time next month as part of a massive test of the emergency broadcast system.

The Federal Emergency Management Agency will hold a nationwide test on Wednesday, Oct. 4 at 2:20 p.m. ET (1:20 p.m. CT).

The tests will be delivered in two parts: the Emergency Alert System, or EAS, and the Wireless Emergency Alerts, or WEA. The EAS portion of the test, the seventh conducted by FEMA, will be sent to radios and televisions. The WEA portion is the third nationwide test and involves a text sent to all cell devices. The text message will be displayed in either English or Spanish, depending on the language settings of the phone.

Televisions and radios will have a message similar to this:

“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.”

Cell phone texts will be along these lines:

“THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.”

According to FEMA, the purpose of the test is to “ensure that the systems continue to be effective means of warning the public about emergencies, particularly those on a national level.”

The tests could be delayed, however, if there is widespread severe weather or other significant events. In that case, the backup testing date is Oct. 11.