The Bell Glossary courtesy of Exodus
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ACD: Automatic
Call Distributor - A system that automatically distributes calls
to operator pools (providing
services such as intercept and directory
assistance), to airline ticket agents, etc.
prediction need for
growth, etc.
AIS: Automatic Intercept System - A system employing an audio-response
unit
under control of a processor to automatically provide pertinent info to callers
routed to intercept.
Alert: To indicate the existence of an incoming call,
(ringing).
ANI: Automatic Number Identification - Often pronounced "Annie," a
facility for
automatically identify the number of the calling party for charging purposes.
Appearance: A connection upon a network terminal, as in "the line has two
network appearances."
Attend: The operation of monitoring a line or an incoming
trunk for off-hook or
seizure, respectively.
Audible: The subdued
"image" of ringing transmitted to the calling party during
ringing; not derived from
the actual ringing signal in later systems.
Backbone Route: The route made up of
final-group trunks between end offices in
different regional center areas.
BHC:
Busy Hour Calls - The number of calls placed in the busy hour.
Blocking: The ratio of
unsuccessful to total attempts to use a facility;
expresses as a probability when computed a
priority.
Blocking Network: A network that, under certain conditions, may be unable
to
form a transmission path from one end of the network to the other. In general,
all
networks used within the Bell Systems are of the blocking type.
Blue Box: Equipment
used fraudulently to synthesize signals, gaining access to
the toll network for the placement
of calls without charge.
BORSCHT Circuit: A name for the line circuit in the central
office. It
functions as a mnemonic for the functions that must be performed by the
circuit: Battery, Overvoltage, Ringing, Supervision, Coding, Hybrid, and
Testing.
Busy Signal: (Called-line-busy) An audible signal which, in the Bell System,
comprises 480hz
and 620hz interrupted at 60IPM.
Bylink: A special high-speed means used in crossbar
equipment for routing calls
incoming from a step-by-step office. Trunks from such offices are
often
referred to as "bylink" trunks even when incoming to noncrossbar offices;
they
are more properly referred to as "dc incoming trunks." Such high-speed means
Cable Vault: The
point which phone cable enters the Central Office building.
CAMA: Centralized Automatic
Message Accounting - Pronounced like Alabama.
CCIS: Common Channel Interoffice
Signaling - Signaling information for trunk
connections over a separate, nonspeech data link
rather that over the trunks
themselves.
CCITT: International Telegraph and
Telephone Consultative Committee- An
International committee that formulates plans and sets
standards for
intercountry communication means.
CDO: Community Dial Office - A
small usually rural office typically served by
step-by-step equipment.
CO:
Central Office - Comprises a switching network and its control and support
equipment.
Occasionally improperly used to mean "office code."
Centrex: A service
comparable in features to PBX service but implemented with
some (Centrex CU) or all (Centrex
CO) of the control in the central office. In
the later case, each station’s loop connects to
the central office.
Customer Loop: The wire pair connecting a customer’s station to the
central
office.
DDD: Direct Distance Dialing - Dialing without operator
assistance over the
nationwide intertoll network.
Direct Trunk Group: A trunk
group that is a direct connection between a given
originating and a given terminating
office.
EOTT: End Office Toll Trunking - Trunking between end offices in different
toll
center areas.
ESB: Emergency Service Bureau - A centralized agency to which
911 "universal"
emergency calls are routed.
ESS: Electronic Switching
System - A generic term used to identify as a class,
stored-program switching systems such as
the Bell System’s No.1 No.2, No.3,
No.4, or No.5.
ETS: Electronic Translation
Systems - An electronic replacement for the card
translator in 4A Crossbar systems. Makes use
of the SPC 1A Processor.
False Start: An aborted dialing attempt.
Fast
Busy: (often called reorder) - An audible busy signal interrupted at twice
the rate of the
normal busy signal; sent to the originating station to indicate
that the call blocked due to
busy equipment.
Final Trunk Group: The trunk group to which calls are routed when
available
high-usage trunks overflow; these groups generally "home" on an office
next
highest in the hierarchy.
Full Group: A trunk group that does not permit
rerouting off-contingent foreign
traffic; there are seven such offices.
Glare:
The situation that occurs when a two-way trunk is seized more or less
simultaneously at both
ends.
High Usage Trunk Group: The appellation for a trunk group that has alternate
higher ranking
office.
Intercept: The agency (usually an operator) to which calls are routed when
made
to a line recently removed from a service, or in some other category requiring
explanation. Automated versions (ASI) with automatic voiceresponse units are
growing in
use.
Interrupt: The interruption on a phone line to disconnect and connect with
another station, such as an Emergence Interrupt.
Junctor: A wire or circuit connection
between networks in the same office. The
functional equivalent to an intraoffice trunk.
MF: Multifrequency - The method of signaling over a trunk making use of the
simultaneous application of two out of six possible frequencies.
NPA: Numbering Plan
Area.
ONI: Operator Number Identification - The use of an operator in a CAMA office
equipped with
ANI.
PBX: Private Branch Exchange - (PABX: Private Automatic Branch Exchange) An
telephone office serving a private customer, Typically , access to the outside
telephone
network is provided.
Permanent Signal: A sustained off-hook condition without activity
(no dialing
or ringing or completed connection); such a condition tends to tie up
equipment, especially in earlier systems. Usually accidental, but sometimes
used intentionally
by customers in high-crime-rate areas to thwart off
burglars.
POTS: Plain Old
Telephone Service - Basic service with no extra "frills".
ROTL: Remote Office
Test Line - A means for remotely testing trunks.
RTA: Remote Trunk Arrangement - An
extension to the TSPS system permitting its
services to be provided up to 200 miles from the
TSPS site.
SF: Single Frequency. A signaling method for trunks: 2600hz is impressed
upon
idle trunks.
Supervise: To monitor the status of a call.
SxS:
(Step-by-Step or Strowger switch) - An electromechanical office type
utilizing a gross-motion
stepping switch as a combination network and
distributed control.
Talkoff: The
phenomenon of accidental synthesis of a machine-intelligible
signal by human voice causing an
unintended response. "whistling a tone".
Trunk: A path between central
offices; in general 2-wire for interlocal, 4-wire
for intertoll.
TSPS: Traffic
Service Position System - A system that provides, under stored-
program control, efficient
operator assistance for toll calls. It does not
switch the customer, but provides a bridge
connection to the operator.
X-bar: (Crossbar) - An electromechanical office type
utilizing a "fine-motion"
coordinate switch and a multiplicity of central controls
(called markers).
There are four varieties:
No.1 Crossbar: Used in large urban office
application; (1938)
No 3 Crossbar: A small system started in (1974).
No.4A/4M Crossbar:
A 4-wire toll machine; (1943).
No.5 Crossbar: A machine originally intended for relatively
small
suburban applications; (1948)
Crossbar Tandem: A machine used for interlocal
office switching.
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