A nationwide test of the UK’s emergency alert service will take place at 3pm on Sunday 23 April.
Messages will pop up on mobile phones across the country, along with a sound and vibration that will stop automatically after 10 seconds.
People will just need to tap “OK” or swipe away the notification like any other, with no further action required.
The alert will make a sound even if a person’s phone is switched on to silent.
It is the first nationwide trial of the service, following pilots in East Suffolk and Reading.
The government said it would be used in “life-threatening emergencies”, including extreme weather events like the wildfires and flooding seen last year.
It has been in production for about three years and notifications could be sent to specific areas, however big or small. For example, everybody in a village where a river was about to burst its banks could be sent a warning alert.
Similar services are already being used in countries like the US, Canada, the Netherlands, Greece and Japan.
It is unlikely to be used during an active terror attack as the attackers would then receive a notification as well, but decisions would be taken when and as needed.
Cabinet Office minister Oliver Dowden said the alert could one day “be the sound that saves your life”.
Read more:
Emergency alerts in other countries – and times they’ve gone wrong…
The government said the test was important as it would make sure people can recognise a real alert, which would provide clear instructions about how to respond in an emergency.
But they are expected to be sent very rarely, only when there is an immediate threat to life, so it may be months or years before anybody receives one.
Assistant chief constable Owen Weatherill, of the National Police Chiefs’ Council, said emergency services would “listen carefully to public feedback” from the test to ensure any future alerts have “a positive impact”.
Concerns for domestic abuse victims
There are concerns the alert could be detrimental to victims of domestic abuse who have a concealed phone hidden from their abuser.
The government said it has been working with organisations who focus on vulnerable women and girls to ensure they are not adversely affected.
People who need their phones to remain concealed have been told they can opt out of the system, or should turn the phone off ahead of 3pm on Sunday.
‘The sound that could save your life’
How to opt out
On iPhones and Android phones and tablets, people can 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”.
Driving concerns
The RAC has raised concerns the alert could cause panic for people driving when it goes off, especially as it is taking place on a Sunday when there are more inexperienced drivers on the road.
Drivers can also be hit with six penalty points and a £200 fine if they hold and use a phone while on the road.
There are concerns drivers will be alarmed by the alert
The government has advised drivers to not look at or touch their phone while at the wheel and should instead find somewhere “safe and legal” to do so before reading the message.
“If there is nowhere safe or legal to stop close by, and nobody else is in the vehicle to read the alert, tune into live radio and wait for bulletins until you can find somewhere safe and legal to stop,” the government has advised.
It added the alert was tested on more than 100,000 people, including those on the M4, “and no such incidents were reported”.
Data worries
The government has said it is not collecting personal data through the alerts.
It explained the system uses cell tower technology to reach phones in a defined geographical area so any compatible device in that area received the message.
No personal information, such as telephone numbers, identity or location is collected by sending the alerts.
If somebody with a UK mobile phone is in another country where they are sending alerts, such as the US, they would get a message in that country using the same broadcast system.
Test will coincide with sporting events
The government has worked with emergency services and other partners, including the Football Association, to ensure it has minimal impact on major events.
It will coincide with some Premier League football matches and the London Marathon, although the majority of runners will have finished by 3pm.
Mark Hardingham, chair of the National Fire Chiefs Council, said: “For 10 seconds, the national test may be inconvenient for some, but please forgive us for the intrusion.
“The next time you hear it – your life, and the life-saving actions of our emergency services, could depend on it.”
