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 on the exterior, allowing anyone to use it without needing to enter. The interior could only be opened with a key, and served as a miniature police station in which officers could read or fill out paperwork, take meal breaks, and temporarily hold detainees until the arrival of transport.