Emergency alert: Everything you need to know as most smartphones to get signal

Brits are to receive a siren sound on their mobile phones and a text message for a test of an emergency alert system.

At around 3pm on Sunday, mobile phones connected to 4G and 5G networks will vibrate and emit the siren sound for up to 10 seconds. Mobile phone users will also receive a message making clear that the alert is a drill. It will mark the second test of the national emergency alert system – after the first in 2023.

The Government has used the system to issue real warnings five times, including in January during Storm Eowyn to warn people in Scotland and Northern Ireland about severe weather.

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Approximately 3.5 million people across Wales and south-west England received an alert during Storm Darragh last December. A 500kg unexploded Second World War bomb found in a Plymouth back garden triggered a warning to some 50,000 phones in February last year.

Messages can be targeted to relatively small areas to pinpoint those at risk. Some 15,000 phones were alerted during flooding in Cumbria in May 2024, and 10,000 received a warning during flooding in Leicestershire in January this year.

The system is designed for use during the most likely emergencies to affect the UK and warnings would also be transmitted on television, radio and locally by knocking on doors.

Pat McFadden, Chancellor of the Duchy of Lancaster, said: “On Sunday September 7, we will hold a UK-wide test of the Emergency Alerts system to ensure it works when we need it most. It is a vital tool for keeping the nation safe when lives are on the line – and every minute matters.

“During Storm Darragh and Storm Eowyn, as millions faced dangerous extreme weather, I saw first-hand how effective it was at getting life-saving advice to at-risk communities in an instant. We do not use the system often, but like the fire alarm in your home, it is always on standby should we need to act.”

But there are concerns that the sound could reveal hidden phones belonging to domestic abuse victims and groups are advising them how to opt out of the alert.

To opt out, iPhone users should go to settings, search for “Emergency Alerts”, and turn off Severe & Emergency Alerts. Android users can do the same by searching “Emergency Alerts” in settings and switching off Severe & Emergency Alerts.

Meanwhile, theatre-goers will be advised to turn their phones off and drivers are urged not to be distracted if they are behind the wheel when the alert takes place.

Emma Pickering, of charity Refuge, said: “During the initial roll-out of the Government’s emergency alert system, Refuge expressed concerns about how the alerts could indirectly impact survivors who have hidden devices by making their abuser aware of the device.

“We must be clear – abuse is always a choice a perpetrator makes, and technology itself is not responsible. When used correctly and as intended, technology can make vast improvements to our lives, and we know that having a hidden device that can be used to access support without fear of being tracked can offer a lifeline for many survivors.

“However, in the hands of a perpetrator of abuse, technology becomes another tool to misuse and weaponise, often with devastating effects.”

A spokesperson for women’s aid charity Solace said: “These alerts may put domestic abuse survivors at risk, if they are concealing devices from perpetrators. Survivors may hide devices because they use them to seek and receive support, or to seek employment to increase their financial independence.”