When is the emergency alert test on mobile phones and can you opt out?
- Published
The national system for sending emergency alerts to mobile phones will be tested for the second time on Sunday 7 September.
The alerts are designed for situations where there is an imminent danger to life, such as during extreme weather events or a terror attack.
The previous test, in April 2023, revealed a number of technical issues - with some people getting the alert more than once and others not receiving it at all.
What time will the emergency alert be sent?
The alert will be sent to millions of devices around 15:00 BST on Sunday 7 September.
Compatible phones - the vast majority of those currently in use - will vibrate and make a siren sound for roughly 10 seconds.
During the first test some users got the alert ahead of the scheduled time while others got it later.
What will the emergency alert say?
The text of the message will read:
"This is a test of Emergency Alerts, a UK government service that will warn you if there's a life-threatening emergency nearby.
"You do not need to take any action. In a real emergency, follow the instructions in the alert to keep yourself and others safe.
"Find simple and effective advice on how to prepare for emergencies at gov.uk/prepare, external.
"Visit gov.uk/alerts, external for more information or to view this message in Welsh. Ewch i gov.uk/alerts am ragor o wybodaeth neu i weld y neges hon yn y Gymraeg."
Which devices will receive the alerts?
The alert will be sent to all smartphones on the UK's 4G and 5G networks, even if they are not connected to mobile data or wi-fi.
There are about 87 million mobile phones in the UK and the goverment says about 95% of the population has 4G or 5G access.
Older phones, and phones connected to 2G or 3G networks, will not receive the message.
Phones that are switched off or in airplane mode will also not get the alert.
During the 2023 test, many mobiles phones on the Three network did not get anything, along with some users on other networks. Others received multiple messages.
The government later confirmed that the alert had not reached around 7% of compatible devices, and promised to address technical issues before future tests.
Watch UK alert go off from a government test in 2023
Can users opt out of receiving emergency alerts?
The government strongly recommends that users enable devices to receive alerts, but it is possible to opt out.
This can be done by searching in your phone's settings for "emergency alerts" and turning off "severe alerts" and "extreme alerts".
The government has published a guide on how to opt out of the test, external.
What is the advice for victims of domestic abuse?
Ahead of the first test, domestic abuse charities warned that the alert system could potentially endanger victims by alerting an abuser to a secret phone.
The National Centre for Domestic Violence advised people with concealed devices to make sure they were turned off for the duration of the test.
What have emergency alerts been used for?
The alert system was used to tell local residents in Plymouth to evacuate after the discovery of a suspected WW2 bomb in a local garden
The government says the alert system plays "a critical role in making sure that we are ready for all kinds of future emergencies".
It uses mobile phone masts to send targeted information to users in a particular area.
Five real life alerts have seen sent to more than seven million mobile phone users, external since the system began.
It was used to contact around 4.5 million phones in Scotland and Northern Ireland during Storm Eowyn in January 2025, and around three million in England and Wales during Storm Darragh the previous month.
It was also used to help co-ordinate the evacuation of more than 10,000 residents in Plymouth as an unexploded 500kg World War Two bomb was carefully removed and taken out to sea to be detonated.