Overview
- The nationwide test, scheduled for Thursday, 10 September, will trigger a Probewarnung at 11:00 and a centrally sent Entwarnung around 11:45.
- For the first time at the federal Warntag, Entwarnung will also be sent via Cell Broadcast so compatible, switched-on phones in a cell receive the all-clear.
- Municipal participation is voluntary, so some places will sound full siren tests (for example Duisburg, Nürnberg and Kreis Wesel) while cities without fixed sirens like Stuttgart will stay silent on that channel.
- Device and technical limits will affect reach because Cell Broadcast needs recent OS support (Android 11+ or iOS 16.1+), phones must be on and not in flight mode, and some siren networks are mid‑migration to new 5G controls.
- Past drills exposed practical faults — for example only 55 of 81 sirens fired in Duisburg during a March test because a 5G control transition was incomplete — and cities such as Dortmund and Leipzig are rebuilding or expanding networks as authorities evaluate results.