**Millions of Mobile Phones to Receive 10-Second Emergency Alert as UK Government Tests Warning System**
In an upcoming nationwide event, millions of mobile phone users across the UK can expect a sudden siren-like alert to sound from their devices for roughly 10 seconds. The government’s emergency alert system is scheduled for another round of testing this year, setting off a cascade of alarms across the country in what is expected to be the final trial for 2025.
Launched initially in 2023, the emergency alert system is a critical tool developed by authorities to quickly inform the public about urgent threats or emergencies that may directly affect their area. The system utilises advanced technology to ensure that warnings are disseminated as widely as possible, with the aim of keeping people safe during potentially dangerous situations.
During the forthcoming test, around 90% of mobile phones operating on 4G or 5G networks are predicted to be triggered. When the alert is sent out, affected devices will vibrate and emit a distinctive, siren-like beep, even overriding any silent or ‘Do Not Disturb’ settings users may have active. Alongside the audio cue, a message will flash up on the phone’s home screen and will be audibly read out, detailing the nature of the emergency alert for a full 10 seconds. Importantly, users will be unable to use other phone functions until they acknowledge receipt of the alert.
Phones that are switched off or set to flight mode will not be impacted by the test. Additionally, users have the option to opt out of receiving these alerts, although authorities strongly encourage public participation in the tests to ensure effectiveness should a real-world emergency occur. For those with older or incompatible devices, authorities have assured that additional channels remain in place to reach those in affected areas.
While the exact date for the test has yet to be announced, government spokespeople have confirmed that this will mark the last system-wide trial for 2025, after which regular testing will continue on a biennial basis to maintain readiness. This test follows incidents earlier in the year, such as the red weather warning for Storm Éowyn in January, when real alerts warned communities of potentially life-threatening conditions caused by extreme winds. At that time, people were advised to stay indoors, avoid driving, and prepare for possible disruption to essential utilities.
The emergency alert system is only authorised for use by designated organisations such as emergency services, government agencies, and departments directly involved in crisis response. The body of the warning message is typically delivered in English; however, in Wales, residents may receive notifications in Welsh as well.
It is noteworthy that alerts are dispatched based solely on users’ current physical locations, rather than addresses or registered home postcodes. Importantly, enabling location services is not a prerequisite for receiving these warnings. The government has urged members of the public, should they ever receive such an alert, to “stop what you’re doing and follow the instructions” stated within the message.
For motorists, dedicated safety guidance has been issued. Drivers are strongly cautioned not to read or interact with emergency alerts while on the road. The official advice is to find a safe and legal place to stop before reading the alert. Alternatively, if stopping safely is not feasible and no one else is present in the vehicle to relay the information, the public are advised to tune into live radio broadcasts for the latest developments.
This alert infrastructure is intended to form a key part of the UK’s broader strategy for keeping the public informed and protected during emergencies, whether the threat be severe weather, public health crises, or other unfolding hazards. Authorities continue to refine the system based on these test exercises, emphasising the balance between broad coverage and minimising disruption to everyday phone use.
As preparations for this latest test continue, officials maintain their commitment to transparency and encourage everyone to be vigilant, follow official advice, and prepare for the possibility of emergency alerts appearing on their devices in the coming weeks.