Specifications

System Overview
IMl66-107
Common Equipment Description
The common equipment base unit is a fully electronic
device. It is essentially a special purpose computer
system acting as a communications controller between
central office (CO), private branch exchange (PBX), or
CENTREX supplied lines and the proprietary digital
telephone stations. The software architecture of the
common equipment provides complete system support
and great flexibility of operation.
The system is fully digital and is ISDN up-gradable
with two usable time slots available for each station.
The digital information passes over time division
multiplexing (TDM) highways. The digital information
is an encoded version of the voice transmission and
control signals that are translated into computer
language. The TDM highway can transmit several
signals over a single pair of wires at the same time.
The signals are governed by a system clock. This
clock creates an overall point of reference against
which the TDM information is synchronized and
partitioned into time slots. A time slot is a portion of
time assigned to a particular position of the system
clock. Each time a particular clock position is reached,
the information associated with that position can be
read. As the system clock goes through the clock
cycle, all necessary digital information is passed
between the pieces of equipment sharing the highway.
The common equipment consists of a base unit, which
provides complete feature support, and optional
expansion modules which provide extended station
and line coverage.
The common equipment is contained in a functional,
modem-style metal housing of contemporary design in
keeping with the needs of the modem off ice
environment. It is engineered to be wall or rack
mounted. The outline dimensions of the common
equipment base units are illustrated in Figure l-l.
l-4