Proprietary devices, like proprietary telephones, are custom made devices for sole use with the associated system. They are used to provide or support additional features not available with the CCU alone.

12.1 Interfaces

Interfaces are items of equipment which allow the system to connect to other networks and systems for which it does not provide a built in connection.

They usually provide two functions. They convert the output of the system to a form suitable for the connected device and back again and provide a protective barrier between the system and the external equipment preventing one from affecting the other adversely.

The following are commonly found in the portfolios of systems today.

12.1.1 - Doorphone

The doorphone interface allows connection to some form of door entry system. It provides connection from line, extension or specialist port giving a speech link to the doorphone and often allows an associated opening device to be triggered from extensions answering calls from the doorphone.

12.1.2 - External Paging

An external paging adapter provides a link from the system to the building’s Public Address (PA) system. It provides an electrically isolated audio path and normally an amplifier control signal to autoselect the correct input to the amplifier when audio is transmitted.

12.1.3 - Analogue Networking And Digital Networking

Analogue networking interfaces allow the system to connect to services such as DC5 and AC15, providing a closer and more functional link than third party converters attached to line or extension ports.

Digital networking interfaces operate in a similar manner to the analogue interfaces, allowing connection to Kilostream, Megastream, ISDN, DPNSS or Q-SIG services.

Systems supporting intersystem networking will include facilities in their software to allow the mapping of dialled digits to extensions or features on the interconnected systems or routing algorithms to break the call out to the public network at the closest point to the destination to assist in reducing costs. These form a near seamless link between the systems and the connected network service.

12.2 - Support Equipment

Support equipment is designed to augment existing system facilities. they are usually used to provide additional power supplies and signalling for the system and its connected extensions. Some examples are outlined below.

12.2.1 - Power Supplies

Power supplies are used to drive equipment that can be connected to the system, but which requires more power than the system’s built in supply can provide. Examples are ring generators and high voltage supplies for network interfaces and detectors.

12.2.2 - Signalling Detectors And Converters

Signalling detectors and converters are required where there is a network connection to the system, which is not provided for in the basic system configuration, or when the system is being connected to a service for which the manufacturer produces no integrated proprietary interface. Their purpose is much the same as the interfaces mentioned above, but their function is usually independent of system software control. Examples include SLT to DC5, DC5 to AC15, SLT to ISDN2, Meter Pulse Detection and DTMF detection.