UK to test cell-broadcast Emergency Alerts

The UK Government will run its next nationwide Emergency Alerts test at 3pm on Sunday, (7 September 2025), leveraging cell broadcast technology to deliver real-time warnings to millions of 4G and 5G devices.

The Emergency Alerts system, formally launched in 2023, uses a geo-targeted one-to-many messaging protocol rather than SMS. Messages are sent directly to all compatible devices connected to cell towers in a defined area, bypassing the need for phone numbers or data connections.

Announcing the next test, Pat McFadden, Chancellor of the Duchy of Lancaster, said: “Emergency Alerts have the potential to save lives, allowing us to share essential information rapidly in emergency situations including extreme storms. 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 platform was developed by Everbridge, a global leader in public warning systems, and deployed in partnership with UK mobile network operators (EE, O2, Three, Vodafone). Everbridge’s system is already live in several European countries, and supports CAP (Common Alerting Protocol) for interoperability with existing flood, weather, and civil defence systems.

Key characteristics of the system include:

• Broadcast, not narrowcast – A single transmission reaches every compatible device in range within seconds.
• Privacy-preserving – No user data, phone numbers, or locations are collected or stored.
• Device behaviour overrides – Alerts trigger a ten-second siren and vibration, even if phones are muted.
• Granular targeting – Messages can be issued nationally or to a radius of a few hundred metres.