AT&T MERLIN LEGEND Installation & Maintenance Manual page 699

Glossary
ISDN 7500B Data Module
A data communications
device that allows connection
between RS-232 data
terminal equipment (DTE)
and the communications
system control unit via MLX
station jacks on the 008 MLX
module. The ISDN 7500B
Data Module is used together
with a modem in a modem
pool to change digital data
signals to analog signals, and
vice versa, which allows
transmission between digital
and analog data stations.
J
jack
A device, accessed by
inserting a plug, that is used
to terminate the permanent
wiring of a circuit.
K
Key
A mode of operation in which
the communications system
uses direct facility
terminations (DFTs) on line
buttons with a separate path
for internal calling.
GL-14 Glossary
L
LED (light-emitting diode)
A semiconductor device that
produces light when voltage
is applied. LEDs show the
operational status of
hardware components, the
results of maintenance tests,
the alarm status of circuit
packs, and the activation of
telephone features.
line coding
The pattern data assumes as
it is transmitted over a
communications channel.
line compensation
An adjustment for the amount
of cable loss in decibels
(dBs), based on the length of
cable between a DS1 module
and a channel service unit
(CSU) or other far-end
connection point.
line/trunk and station module
A module on which the jacks
for connecting central office
(CO) lines/trunks and/or the
jacks for connecting the
stations are located.
line and trunk assignment
The assignment of lines and
trunks connected to the
communications system
control unit to specific
buttons on each telephone.