A message that will be sent to mobile phones during the second national test of the Emergency Alerts system was revealed on 28 July.
Millions of mobile devices will vibrate and make a siren sound for around 10 seconds at approximately 3:00pm on Sunday 7 September along with a text.
The national test of the Emergency Alerts system was announced by Chancellor of the Duchy of Lancaster, Rt Hon Pat McFadden, last month, alongside a new Resilience Action Plan to improve the way the government prepares for and responds to emergencies.
The message, which will be sent to all 4G and 5G phone networks in the UK, will make clear that this is a test and no further action is required.
The test will be the second of its kind, and follows a government commitment to test the system regularly to make sure it works optimally and familiarise the public with the alerts.
Ahead of the national test, the government is running a public information campaign to notify people it is taking place, including communications targeted at vulnerable groups such as victims of domestic abuse. The campaign has also featured the first national information video in British Sign Language.
Since the first national test of the Emergency Alerts system in April 2023, five alerts have been sent, including during major storms when lives were at risk.