Overview

• The government will trigger a 10-second loud siren and vibration on every compatible 4G/5G phone later in 2025, with the exact date to be confirmed
• Since its 2023 launch, the system has issued four genuine alerts, notifying the public of bomb threats in Plymouth, flooding in Cumbria and Storm Darragh
• Officials confirm this will be the last mass test of 2025 before drills move to a biennial schedule to maintain national preparedness
• Alerts will override silent and do-not-disturb modes but can be disabled via emergency alert settings on both iOS and Android devices
• Cabinet Office and security services have worked with mobile operators to address past delivery issues and stress the test is intended to build resilience rather than cause panic