The UK Government will be conducting a nationwide test of the Emergency Alert System.
Planned to heppen on Sunday, 23 April at 3pm.
The aim of the system is to alert people about emergencies and provide guidance on how to stay safe.
Customers will receive a loud and distinct alert on their phones and tablets, and the message will appear on their screen until it is acknowledged.
Emergency Alert System work on all 4G and 5G mobile networks, and customers can opt out of the service if they choose to, although the Government recommends against opting out as this service is intended to warn people when lives are in danger.