Why a 10-second siren will sound on your phone on 7 September
Related: Moment BBC newsreader interrupted by emergency alert live on air
The UK's Emergency Alert System is scheduled for its second national test on 7 September at 3.00pm, with millions of mobile phones expected to receive the alert.
Smartphones will vibrate and sound a 10-second siren, displaying a test message, as part of a system designed to warn the public of nearby life-threatening emergencies such as extreme weather or terror activity.
This test, the first since April 2023, is intended to strengthen the country's emergency preparedness, a measure recommended by the Covid inquiry.
Concerns about the alert's impact on domestic abuse victims using secret phones have led to government plans for a public information campaign on how to disable the alert.
Since April 2023, the system has been activated five times for real emergencies, including during major storms and the discovery of an unexploded Second World War bomb in Plymouth.