Police Box

A police box is a public telephone kiosk or callbox for the use of members of the police, or for members of the public to contact the police. It was used in some countries, most widely in the United Kingdom throughout the 20th century from the early 1920s. Unlike an ordinary callbox, its telephone was located behind a hinged door so it could be used from the outside by anyone, and the interior of the box was, in effect, a miniature police station for use by police officers to read and fill in reports, take meal breaks and even temporarily hold detainees until the arrival of transport.

The typical British police box contained a telephone linked directly to the local police station, allowing patrolling officers to keep in contact with the station, reporting anything unusual or requesting help if necessary. A light on top of the box would flash to alert an officer that they were requested to contact the station.

Source: Wikipedia