An intercom, also known as an intercommunication device, talkback system, or doorphone, is a stand-alone communication system designed to facilitate two-way voice communication within a building or a small network of buildings, such as an office complex or apartment block. Intercoms are commonly used in settings where direct communication between different rooms, floors, or entry points is necessary without relying on external phone networks.

This system consists of audio and, in more modern versions, video components that allow users to interact efficiently. Basic intercoms use speakers and microphones to transmit voice signals, enabling real-time conversations between individuals in separate locations. More advanced intercom systems include video capabilities, which allow users to see each other through built-in cameras, adding an extra layer of security, particularly for monitoring entry points.

Often installed at building entrances to allow communication between a visitor and a resident or security personnel before granting access. For example, in residential buildings, a visitor can use the intercom to request entry, and the resident can communicate with them, see them (in the case of a video intercom), and unlock the door remotely if necessary.