    .                        The Bell Glossary -                        ..
    .                               by                                  ..
    .                         /\<\     /\<\                             ..
    .                        </\>\>ad </\>\>arvin                       ..

ACD: Automatic Call Distributor - A system that automatically distributes 
     calls to operator pools (providing services such as intercept and direc-
     tory assistance), to airline ticket agents, etc.

Administration: The tasks of record-keeping, monitoring, rearranging, predic-
     tion 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 func-
     tions 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 are necessary to assure that the first incoming 
     pulse is not lost.
        
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 Inter-
     national committee that formulates plans and sets standards for inter-
     country 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 sta-
     tion 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 for-
     eign 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 
     routes via other similar groups, and ultimately via a final trunk group 
     to a 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 catego-
     ry requiring explanation. 
        
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 
     to verbally obtain the calling number of a call originating in an office 
     not 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 some-
     times 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.
