National Mobile Emergency Alert System: Upcoming Test Announced for September

The UK government has announced that the national emergency alert system for mobile phones will undergo another test across the country this September. This follows a previous nationwide trial in 2023 which encountered some technical difficulties.

The upcoming test is scheduled for 15:00 BST on September 7th. During this time, all compatible mobile phones will vibrate, emit a distinctive siren sound for ten seconds, and display an emergency message. This alert will activate even if your phone is set to silent.

These alerts are designed to notify the public about immediate threats to life, such as extreme weather events or terror attacks.

While the system has been used regionally on five prior occasions for specific incidents, the last nationwide test in 2023 revealed several issues. Some individuals received the alert earlier than expected, others did not receive it at all, and some even got multiple notifications. Notably, many users on the Three network, along with some on other networks, reported not receiving the alert. The government later confirmed that the message failed to reach approximately 7% of compatible devices.

The Cabinet Office stated at the time that these problems would be thoroughly reviewed and addressed before any future tests. The purpose of September's test is to confirm the system's operational effectiveness and to ensure the public is familiar with these alerts, aligning the UK with practices in other nations like the US and Japan that utilize similar systems.

Out of the roughly 87 million mobile phones in the UK, only smartphones connected to 4G or 5G networks will receive the alert. Older devices, or those linked to 2G or 3G networks, will not be notified.

Cabinet Office Minister Pat McFadden emphasized the importance of testing, stating: "Just like the fire alarm in your house, it's important we test the system so that we know it will work if we need it."

The emergency alert system has already proven its value in various real-world scenarios. It was activated to send notifications to 4.5 million phones in Scotland and Northern Ireland during Storm Eowyn in January 2025, and to 3.5 million devices in England and Wales during Storm Darragh the month prior.

Please note that devices not connected to mobile data or Wi-Fi will still receive the alert. However, if your phone is switched off or set to airplane mode, it will not.

Domestic abuse charities have previously raised concerns that such alerts could inadvertently reveal a hidden phone to an abuser. The National Centre for Domestic Violence advises individuals with concealed phones to power them off for the duration of the test. While the government encourages keeping emergency alerts enabled, they have published an external guide for domestic abuse victims on how to opt out if necessary.

Additionally, this new test will incorporate a version of the alert message in British Sign Language for deaf individuals.