The new Emergency Alerts system will be tested nationally on April 23rd.
The system will warn people when their lives are in danger. An Emergency Alert is a loud, siren-like sound with a message on your mobile phone screen.
To find out more, visit gov.uk/alerts
The test alert on 23 April will be sent to most mobile phones across the UK. Devices will make a distinct, siren-like sound for up to 10 seconds, including on phones switched to silent mode. Phones will also vibrate and display a message about the test. The aim is to alert the country to the test and reassure you that no action needs to be taken.