A door phone or door bell phone is a set of

electrical Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

and

electronic Electronic may refer to: *Electronics, the science of how to control electric energy in semiconductors * ''Electronics'' (magazine), a defunct American trade journal *Electronic storage, the storage of data using an electronic device *Electronic c ...

elements used to handle communication between a resident in a

house A house is a single-unit residential building. It may range in complexity from a rudimentary hut to a complex structure of wood, masonry, concrete or other material, outfitted with plumbing, electrical, and heating, ventilation, and air c ...

apartment An apartment (American English, Canadian English), flat (British English, Indian English, South African English), tenement (Scots English), or unit (Australian English) is a self-contained housing unit (a type of residential real estate) that ...

villa A villa is a type of house that was originally an ancient Roman upper class country house that provided an escape from urban life. Since its origins in the Roman villa, the idea and function of a villa have evolved considerably. After the f ...

and a guest outside. The device can also lock or unlock the

door A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide securit ...

it has been configured to work with. Door phones have been used across a variety of commercial and residential

building A building or edifice is an enclosed Structure#Load-bearing, structure with a roof, walls and window, windows, usually standing permanently in one place, such as a house or factory. Buildings come in a variety of sizes, shapes, and functions, a ...

s. For example, offices and apartment blocks both make frequent use of door phones. They are so widely used that, nowadays, they form part of the standard electrical installation of most buildings.Door phones reference manual
/ref> The simplest version is an

intercom An intercom, also called an intercommunication device, intercommunicator, or interphone, is a stand-alone voice communications system for use within a building, small collection of buildings or portably within a small coverage area, which funct ...

that establishes a communication between an entryway at street level and a resident inside the house. A

loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...

installed at the street level entrance allows a building resident to speak to their visitor. In buildings where there are more than one door phone plate located outside of a building's entrance, each door phone has a certain number of buttons depending on the number of units in each building.

Operation

A door phone in its most basic version is a two-way

allowing communication from the street to the inside of a building. More complex door phones are connected to electric strikes, and can unlock and open the door to allow access to the interior of the building. The part of the door phone on the exterior of a building is known as the ''door phone plate''. It is located at the outside of the entrance of each building. Door phone plates consist of a matrix of

button A button is a fastener that joins two pieces of fabric together by slipping through a loop or by sliding through a buttonhole. In modern clothing and fashion design, buttons are commonly made of plastic but also may be made of metal, wood, or ...

s. each of them drive a

buzzer A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric (''piezo'' for short). Typical uses of buzzers and beepers include alarm devices, timers, train and confirmation of user input such ...

located in a unit inside each apartment building. Each apartment building contains a button that can activate the

electric strike An electric strike is an access control device used for door frames. It replaces the fixed strike faceplate often used with a latch (also known as a ''keeper''). Description Like a fixed strike plate, an electric strike plate normally prese ...

. There are several installation systems, the most traditional being a system known as ''4 + 1'', named for the types of wiring that it requires. A 4 + 1 system requires four wires that handle power, communication, and the door system, and another wire for communication between an in-unit apartment resident and the person using the door phone.

Video door phones

Going a little further in time, we find video door phones featuring a video installation apart from the classical audio. In these cases, the intercom plate has the same structure as the previous version but features a

video monitor A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signa ...

connected to a surveillance camera that allows inspecting the person who pressed the button and part of the surrounding area. Access control systems. Some manufacturers have also adopted the possibility of opening the door via a keyboard. By introducing a numerical secret code the

is operated. Although there is also the possibility of being used as an access control with either a

magnetic card The term digital card can refer to a physical item, such as a memory card on a camera, or, increasingly since 2017, to the digital content hosted as a virtual card or cloud card, as a digital virtual representation of a physical card. They shar ...

or a

smart card A smart card (SC), chip card, or integrated circuit card (ICC or IC card), is a card used to control access to a resource. It is typically a plastic credit card-sized card with an Embedded system, embedded integrated circuit (IC) chip. Many smart ...

Wiring topology

Among other classifications there is one with three different types of door phones that differ mainly in the number of wires required in their installation, having some parallelism between different manufacturers, that use different communication protocols but a similar wiring topology: * Conventional: This system is characterized by the use of four wires plus of wires for each home. That is, (4 + "n") wires, where "n" indicates the number of homes. This system is best suited for medium-sized buildings. * Simplified: This system is characterized by using a wire pair, plus the number of homes in threads. That is, (1 + "n") wires, where "n" indicates the number of homes. It is best suited for medium-sized buildings with two or three entrance gates. * Digital: This system more suitable for use in large buildings or complex installations, as it ensures maximum capacity and ease of installation. It is characterized for using only two wires for all facilities.Digital door phones -2 wire
/ref>

References

{{commonscat Security Telecommunications equipment

Operation

Video door phones

Wiring topology

See also

References