On October 4, 2023, a nationwide emergency alert test in the U.S. was sent to most modern cell phones, televisions, and radios that were turned on and connected at that time.

What devices went off?

These were the main types of devices that received or broadcast the test:

  • Cell phones / smartphones
    • Any Wireless Emergency Alert (WEA)–compatible phone on participating U.S. carriers could receive the alert, as long as it was powered on, within range of a cell tower, and not in airplane mode.
* This included most recent iPhones and Android phones, plus many pay‑as‑you‑go and prepaid devices that support WEA.
  • Televisions
    • TVs connected to broadcast, cable, or satellite services participated through the Emergency Alert System (EAS).
* Whatever channel people were watching at that moment was briefly interrupted to show the test message.
  • Radios
    • AM/FM radios receiving over‑the‑air programming also broadcast the test via EAS.
* Any radio tuned to a participating station at the time of the test would have played the alert audio.

In short, if you were in the U.S. and had a WEA‑capable phone on, or you were watching TV or listening to the radio around 2:20 p.m. Eastern on October 4, 2023, those devices were designed to go off with the test alert.

Information gathered from public forums or data available on the internet and portrayed here.