Overview
- The federal BBK will trigger a nationwide probe warning through the Modular Warning System at 11:00 on Thursday, September 10, 2026, and plans an Entwarnung (all-clear) for about 11:45.
- MoWaS will send the probe text to warn‑multipliers such as radio, TV and app servers while Cell Broadcast will deliver the message directly to millions of mobile phones without an app.
- Cell Broadcast can now carry Entwarnung messages after a feature update introduced in late November 2025, so both warning and all-clear will be tested over the same mobile channel.
- The federal warning system stays available for real emergencies during the test so authorities can issue genuine alerts alongside the scheduled probe at any time.
- Participation is voluntary so local channels will vary: some cities will use sirens and loudspeakers while others, for example Stuttgart, rely on Cell Broadcast, apps and radio, and the BBK asks citizens to give feedback from September 10–17, 2026.