ATT DEFINITY Communications System Generic 3 Instructions Manual

Glossary
Issue  3   March 1996GL-13 
digital transmission
A mode of transmission in which the information to be transmitted is first converted to digital form 
and then transmitted as a serial stream of p ulses.
digital trunk
A circuit in that carries digital voice and/or digital data in a telecommunications channel.
dial-repeating trunks
A PBX tie trunk that is c apable of handling PBX station signaling information without attendant 
assistance.
direct agent
A switch feature accessed only via Adjunct...

Glossary
GL-14Issue  3   Marc h 1996 
duplicated common control
Two pro c essors ensuring c ontinuous operation of a c ommunic ations system. While one processor 
is on-line, the other functions as a b ackup. The backup processor g oes on-line period ically or 
when a pro blem condition occurs.
duplication
The use of redundant c omponents to improve availab ility. When a duplic ated subsystem fails, its 
backup redundant system automatically takes over.
duplication option
A system op tion that duplicates...

Glossary
Issue  3   March 1996GL-15 
enhanced private-switched communications service (EPSCS)
An analog private tele communications network based on the No. 5 Crossbar and 1A ESS that pro-
vides advanced voice and data telecommunications services to companies with many locations.
Erlang
A unit of traffic intensity, or load, used to express the amount of traffic it takes to keep one facility 
busy for one hour. One Erlang is e qual to 36 CCS. See also Hundred Call Seconds.
expansion archangel (EAA)
A...

Glossary
GL-16Issue  3   Marc h 1996 
F
facility
A g eneral term used for a telecommunic ations transmission pathway and associate d equipment.
facility associated signaling (FAS)
Signaling in which a D-channel carries the sig naling only for those channels on the same physical 
interface.
feature
A specifically defined function or service provided by the system.
feature button
A labeled button on a telephone or attendant console used to access a specific feature.
fiber optics
A technology using...

Glossary
Issue  3   March 1996GL-17 
Generic 3 Management Terminal (G3-MT)
DEFINITY Communications System Generic 3 Management Terminal, a management terminal 
used for system administration and maintenance in the switch room or optionally at some dis-
tance from the switch.
generalized route selection (GRS)
An enhancement to Automatic Alternate Routing/Automatic Route Selec tion (AAR/ARS) that per-
forms routing based on c all attributes, such as Bearer Capability Classes (BCCs), in addition to 
the a...

Glossary
GL-18Issue  3   Marc h 1996 
hop
Nondirect communication between two switch communications interfa ces (SCIs) where b y the SCI 
message passes automatically without interme diate processing through one or more intermediate 
SCIs.
host computer
A computer, c onnected to a network, that processes data from d ata-entry d evices.
hunt group
A group of extensions that are assig ned the Station Hunting feature so that a call to a b usy exten-
sion will reroute to an idle extension in the group.
I...

Glossary
Issue  3   March 1996GL-19 
The most common arrangement of channels in ISDN-PRI i s  2 3  64-kbps B-channels for transmit-
ting voice and data and one 64-kbps D-channel for transmitting associated B-channel call control 
and out-of-band signaling information 
— an arrangement called ‘‘23B+1D,’’ although with nonfa-
cility-associated signaling (NFAS) ISDN-PRI can include 24 B-channels and no D-channel. See 
also Integrated Services Digital Network and Integrated Services Digital Network Basic...

Glossary
GL-20Issue  3   Marc h 1996 
L
light-emitting diode (LED)
A semic onductor device that produces lig ht when voltage is a p plied. LEDs provid e a visual indi-
cation of the o perational status of hardware components, the results of maintenance tests, and 
the alarm status of circuit packs, and the activation of telephone features.
lightwave transceiver
Hardware that provides an interface to fiber-optic c able from port circ uit packs and digital signal 
level-1 (DS1) converter circuit packs....

Glossary
Issue  3   March 1996GL-21 
maintenance
The activities involved in keeping a telecommunications system in proper working c ondition: the 
detection and isolation of software and hardware faults, and automatic and manual recovery from 
these faults.
management terminal
The terminal that is used  b y the system administrator to a dminister the switc h. The terminal may 
also be used to a ccess the BCMS feature.
major alarm
An in dic ation of a failure that has caused critic al degradation of...

Glossary
GL-22Issue  3   Marc h 1996 
multiappearance voice terminal
A terminal equipped with several call a ppearance buttons for the same extension number, allow-
ing  the user to handle more than one c all, on that same extension number, at the same time.
multicarrier cabinet
A structure that hold s one to five carriers. See also single-carrier cabinet.
multifrequency-compelled (MFC), release 2 (R2) signalling
A sig nal consisting of two frequency components, such that when a signal is transmitted...