FEMA stated in the press release that any cell phones connected to a network between 2:20 p.m. and 2:50 p.m. will also receive a message saying, "THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed."

The message will display in either English or Spanish, depending on your phone settings. The tone and vibration are included to ensure that the alert is accessible to the entire public, including people with disabilities.

However, phones that are switched off within this time frame will not receive a message, tone or vibration. 

Scheduled simultaneously, the EAS portion of the test will last approximately one minute on televisions and radios. The alert will be accompanied by a message similar to the WEA alert, as well as another tone to distinguish itself from other emergecy messages.

"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 the national level," FEMA said in the release. "FEMA and the FCC are coordinating with... other stakeholders... to minimize confusion and maximize the public safety value of the test."

It will mark the seventh nationwide test of EAS since 2011 and third nationwide test of WEA. 

If the Oct. 4 test is postponed because of "significant events," such as widespread severe weather, the testing date will be resheduled to Oct. 11.

For more information on the Emergency Alert System, visit fema.gov.