AT&T MERLIN LEGEND Release 3.1, System Programming Manual

Page: 850 / 887

Glossary
System Programming
GL–3
Automatic Route
Selection See ARS .
automatic-start tie
trunk Tie trunk on which incoming calls are routed to an operator
or other designated destination without a start signal, as
soon as the trunk is seized; the destination is specified
during programming. Also called “automatic ringdown” or
“auto-in” tie trunk.
auxiliary power unit Device that provides additional power to the system.
B
B8ZS
(bipolar 8 zero substitution) Line-coding format that
encodes a string of eight zeros in a unique binary
sequence to detect
bipolar violation
. See also
bipolar
signal
.
backup
Procedure for saving a copy of system programming onto
a floppy disk or
memory card
. See also
restore.
bandwidth
Difference, expressed in hertz, between the highest and
lowest frequencies in a range that determines channel
capacity.
barrier code
Password used to limit access to the
Remote Access
feature of the system.
basic carrier
Hardware that holds and connects the
processor
,
power
supply
, and up to five modules in the system. See also
expansion carrier
.
baud rate
Strictly speaking, a measurement of transmission speed
equal to the number of signal level changes per second. In
practice, often used synonymously with
bit rate
and
bps
.
B-channel
(Bearer-channel) 64-kbps channel that carries a variety of
digital information streams, such as voice at 64 kbps, data
at up to 64 kbps, wideband voice encoded at 64 kbps,
and voice at less than 64 kbps, alone or combined
.
Bearer-channel
See
B-channel
.
Behind Switch
mode
One of three modes of system operation, in which the
control unit is connected to (behind) another telephone
switching system, such as
Centrex
or Definity, which
provides features and services to telephone users. See
also
Hybrid/PBX mode
and
Key mode
.