Overview
- The Bundesamt für Bevölkerungsschutz (BBK) will trigger a central Probewarnung over MoWaS at 11:00 on Thursday and issue an Entwarnung at about 11:45, and it will run an online citizen survey about the test until September 17.
- For the first time at the Warntag Entwarnung can be sent via Cell Broadcast, a mobile‑network service introduced in November 2025 that pushes messages directly to switched‑on phones in a target cell without requiring a warning app.
- Participation by states, districts and municipalities is voluntary so some local sirens and channels will not be activated; states report large but uneven siren stocks and new funding, for example Bavaria >11,000 sirens, Hesse 4,074, Mecklenburg‑Vorpommern ~1,700 and Schleswig‑Holstein about 2,800 with €23.2 million pledged to 2030.
- Cell Broadcast reaches many phones but will not work if a device is switched off, in flight mode, outside a coverage cell or running an unsupported operating system version such as older than Android 11 or iOS 16.1.
- The Warntag is both a technical stress test and a public drill designed to reveal failures in apps, radio links, siren triggers and local procedures so authorities can prioritise analogue fallbacks, siren upgrades and digital fixes based on direct citizen reports.