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.
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
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.
An external paging adapter provides a link from the system
to the buildings 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.
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.
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.
Power supplies are used to drive equipment that can be connected
to the system, but which requires more power than the systems
built in supply can provide. Examples are ring generators
and high voltage supplies for network interfaces and detectors.
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.