The test will be run as part of an effort to ensure that alert systems in the U.S. continue to be effective in communicating to the public critical information regarding emergencies, especially on a regional level.

FAQs on the test alert:

Is there a cost to receive the test? No.

Do you need to sign up to receive the test? No; all phones within the vicinity should receive the test.

Can the test monitor, locate, or lock my phone? No. 

Can the test gather my private data? No. The alert system is a broadcast technology and does not collect data. 

Will the test interrupt a phone call? No.

Will the test override my phone's settings if it is set to silent/vibrate? No. 

If I am out of town, will I still receive the test? No; you must be within the South Bay broadcast region to receive it; so if you are, for instance, in Downtown Los Angeles, you will not receive it.

I didn't receive the alert - Why not? Your phone must be Wireless Emergency Alert compatible, switched on, not in airplane mode, within reach of a cell tower, and on a network where the wireless provider is capable of receiving the wireless emergency alert message. Also, if your phone is turned off when the message is sent and is not turned back on until after the message expires, you will not receive the message. 

Is it true that the alerts use high frequency signals that activate harmful nanoparticles such as graphene oxide? No. The audio signal is the same combination of audio tones used since 1963 by the original Emergency Broadcast System. The tones are used by more than 1,700 local agencies for their emergency alert systems and are not known to cause any harm.

Will the emergency alert turn me into a zombie? No.