Overview

• Compatible phones and tablets on 4G or 5G will vibrate, play a siren for about 10 seconds and show a test message even if set to silent.
• Only authorised bodies can send alerts, and the government has issued opt-out guidance along with resources for vulnerable users, including British Sign Language materials.
• Motorists are warned not to touch their phones during the alert, as using a hand‑held device while driving is illegal and can result in a £200 fine and six penalty points.
• The test will be issued by COBR under the government’s Resilience Action Plan after earlier nationwide testing in 2023 saw roughly 7% of compatible devices miss the alert.
• The system has already been used for severe weather and local emergencies, including a Storm Éowyn activation that reached about 4.5 million people in January 2025.