The UK government is set to conduct a nationwide emergency alert test on September 7, 2025, around 3 pm, sending a loud siren and a brief message to most mobile devices across the country.

During this second test of the emergency alert system, every active mobile phone on 4G and 5G networks will receive the alert, which will include a siren sound, vibration, and a message indicating it is a drill.

The alert will be broadcast in both English and Welsh and is designed to notify people in the vicinity of a potential life-threatening emergency, with the message reassuring recipients that it is a test and no action is needed.

The system has previously been activated for real emergencies, such as severe weather events like Storm Eowyn and Storm Darragh, as well as incidents like a WWII bomb discovery and flooding alerts.

The emergency alert system can target specific areas and is disseminated via TV, radio, and door-to-door notices, ensuring broad coverage during actual emergencies.

Pat McFadden, the Chancellor of the Duchy of Lancaster, emphasized the importance of testing the system, comparing it to a household fire alarm, and highlighted its potential to save lives during dangerous weather and other emergencies.

He also noted that the system's previous real-world use during extreme weather events underscores its significance for public safety.

Since April 2023, the system has been activated five times for various emergencies, including storms, a WWII bomb, and floods, to ensure readiness for future crises.

The primary goal of this nationwide test is to confirm the system's preparedness for future emergencies when lives could be at risk.

The alert message will be sent in both English and Welsh to mobile phones on 4G and 5G networks, with the aim of notifying people in the vicinity of a life-threatening emergency.

During the test, devices connected to 4G and 5G networks will vibrate and emit a siren sound for up to 10 seconds, accompanied by a clear message indicating it is a drill.

Some MPs have called for diversifying emergency communication methods, suggesting additional measures like pamphlets for those without mobile access.