The government has reminded people that an emergency alert is to be sent to millions of phones across the country in September.
Mobile phone and tablet users across the UK will hear their devices make a loud siren-like sound, something that would allow the UK government to warn of any potential danger to life nearby.
During the test, the second only of its kind, approximately 87 million mobile devices will vibrate and make a loud siren sound for roughly ten seconds, even if they are set to silent. A message will also appear on phone screens, making it clear the alert is only a test and no action needs to be taken.
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.
The test is due to happen at 3pm on Sunday 7th September.
The government said it is testing the system to ensure it is working optimally and so the public become familiar with the alerts.
When has the system been used for real?
Since the first national test of the system in April 2023, five alerts have been sent to warn the public of real emergencies.
The largest ever use of the system happened in January this year, when approximately 4.5 million people in Scotland and Northern Ireland received an alert during Storm Eowyn, after a rare red weather warning - meaning there was a risk to life - was issued.
How to turn the alert off
Domestic violence charities have expressed their concern the the alert could give away secret phones of people experiencing abuse are keeping hidden.
Anyone who has any concerns is advised that the alert can be avoided.
On iOS and Android devices, search settings for "emergency alerts" and turn off "severe alerts" and "emergency alerts".
On Huawei devices running EMUI 11 or older, search settings for "emergency alerts" and turn off "extreme threats", "severe threats", and "show amber alerts".
The other option is switching off the device entirely or putting it in aeroplane mode before 3pm.
