Britain will send out a "loud siren-like" notice to all phones in the nation.

The UK government has launched an emergency warning system to protect the public against a range of threats. The system will be tested nationwide in the early evening on April 23 and will cause any phone connected to a 4G or 5G mobile network to vibrate and be accompanied by a loud siren-like sound for up to ten seconds. After the test, real warning messages will focus on severe weather related-incidents such as flooding or wildfires. Similar systems are already in use in the US, Canada, Japan, and the Netherlands. Those who don't want their Sunday evening interrupted by a government klaxon can switch emergency alerts off in their phone's settings menu.