A third party device is a piece of equipment to be used with
a telephone system to perform a specific task, but is not
produced by the manufacturer themselves. This means that SLT
extensions from other manufacturers are, strictly speaking,
third party devices. However the term is usually applied to
non-extension devices attached to the system to provide a
special facility unavailable using only the manufacturers
There are two reasons to use third party equipment with a
telephone system. The first is to provide a facility which
is not inherent within the system itself. Secondly, the third
party device may do a simialr job as a manufacturers
unit, but augment the features of the system further.
Examples of these types of equipment are, Music On Hold units,
Voicemail, External Paging systems, Radio Paging systems and
Call Logging systems.
Third party devices attach to the system via extension, line
ports or private networking connections. It is important that
the correct type of connection is made to ensure that the
isolation requirement and functionality remain unimpaired.