Mobile phones across the UK will be sent an emergency alert as the government tests the system nationwide.
During the test, the second only of its kind, approximately 87 million mobile devices will ring out unprompted.
The system was first tested in April 2023, but the government said some users reported that their phones did not sound, with the problem traced back to specific networks.
It has also been used on several occasions to warn of adverse weather events and in one case last year, when an unexploded Second World War bomb was due to be moved by the military.
Here is what you can expect.
When is it going to happen?
The test is due to happen at 3pm on Sunday 7 September.
Phones will vibrate and emit a loud siren sound for roughly 10 seconds, even if they are set to silent.
A message will also appear on phone screens warning people it is only a test and no action needs to be taken.
The government said it is testing the system to ensure it is working optimally and so the public become familiar with the alerts.
But critics have said the alerts themselves could put people’s safety at risk, including drivers who may become distracted and domestic violence victims who keep a secret phone.
Pat McFadden, the chancellor of the Duchy of Lancaster, said: “It’ll be a really important moment where we can do the equivalent at a national level of…
