Audio Door Phone

A Door Phone or door bell phone is a set of electrical and electronic elements used to handle two-way communication (street to home) in houses, apartments or villas. The device is connected to a secure communication system used to control the opening of the door giving access to any kind of buildings, offices, or apartment blocks. They are so widely used in the mentioned structures, that nowadays, they form part of the standard electrical installation of most buildings.

The simplest version is a simple intercom that establishes a communication between the street door and the house. In buildings where there are more than one door phone plate (located at the outside of the building's door entrance) has a certain number of buttons, depending on the number of flats existing in each building, in addition to the loudspeaker.