Intercom systems can consist of different types of intercoms and sub-systems. The basic system types can be categorised by end user (i.e. commercial, residential, and infrastructure types such as 2-wire or IP). The addition of video alongside an audio element provides a greater level of visual verification with the caller. Intercom systems are wired separately from any other communication systems, such as public announcement or telephone systems.
Intercom door stations are generally located at external entry points and provide a means of requesting access from a building’s operators following ID verification. They can also take the form of assistance points in parking areas.
Intercom systems require integration with the door or barrier they control. This may involve a relay trigger to open an electric door lock or to raise a barrier to allow vehicles access to loading areas.
All door stations communicate with a base station (or stations) in a commercial environment, or an apartment in a residential environment depending on the system topology. Communication is generally duplex (i.e. two-way and similar to a telephone call) or simplex (i.e. one person is able to speak at a time).
More complex IP solutions reside on a dedicated network and can therefore be distributed over the standard telephone system (SIP) in a commercial building, or reside on an intelligent building’s platform to serve as a one stop solution for tenants in residential buildings. The complexity of the system can increase again when the activation of the intercom’s ‘call’ function places a local CCTV camera into record mode to monitor for misdemeanours. These integrations are commonly used in residential and commercial environments.