Overview

• The 3pm drill sent a 10-second siren and on-screen message to most 4G/5G devices, with the prime minister calling the exercise successful.
• Some people reported not receiving the alert, which does not reach devices that are off, in airplane mode, on 2G/3G or on non‑compatible handsets, with performance checks now under way.
• Sporting fixtures briefly paused or adjusted timing during the alert, including rugby league in Hull and cricket in Southampton, after prior warnings to spectators.
• The system broadcasts from mobile masts without collecting personal data, and has issued five real warnings since 2023, including 4.5 million during Storm Éowyn and 3.4 million during Storm Darragh.
• Officials promoted opt-out guidance and safety advice, with domestic‑abuse charities urging survivors with secret phones to disable tests or power devices off.