The President can send a Presidential Alert to all cell phones. This cannot be turned off by the user. https://www.wired.com/story/presidential-text-alert-fema

The President can send a Presidential Alert to all cell phones. This cannot be turned off by the user. https://www.wired.com/story/presidential-text-alert-fema-emergency-history/ https://www.wired.com/story/presidential-text-alert-fema-eme...