ATT DEFINITY Communications System Generic 3 Basic Call Management System Instructions Manual

Glossary
Issue  4  September 1995GL-11 
data link
The configuration of physi cal facilities enabling end terminals to communicate directly with each 
other.
data module
An interconnection device between a basi c rate interface (BRI) or digital communications proto-
col (DCP) interfac e of the switch and data terminal equipment (DTE) or data communications 
equipment (DCE).
data path
The end-to-end  connection used for a data-communications link. A data path is the combination 
of all the elements of an...

Glossary
GL-12Issue  4  September 1995 
dial-repeating tie trunk
A tie trunk that transmits called-party addressing information between two communications sys-
tems.
digit conversion
A process used to convert specific dialed numbers into other dialed numbers.
digital communications protocol (DCP)
An AT&T proprietary protocol used to transmit both d i gitize d voice and  digitized data over the 
same communications link. A DCP link is made up of two 64 ~k b ps information (I-) channels and  
one 8-kbps...

Glossary
Issue  4  September 1995GL-13 
Direct Inward Dialing (DID)
A feature that allows an incoming call from the public network (not FX or WATS)  t o  reach a spe-
cific telephone without attendant assistance. DID calls to DID-restricted telephone lines are 
routed to an attendant or recorded announcement, depending on the option selected.
direct inward dialing (DID) trunk
An incoming trunk used for dialing  d irectly from the public network into a c ommunications system 
without help from the...

Glossary
GL-14Issue  4  September 1995 
E
E1
A digital transmission standard that carries traffic at the rate of 2.048 Mbps.
The E1 facility is  divid e d into 32 channels (DS0s) of 64 kb p s information numbered from 0 ~to 31. 
Channel 0 is reserved for framing and synchronization information. When a D-channel is  present, 
it occ u pies channel 16.
ear and mouth (E&M) signaling
Trunk supervisory signaling, used between two communications systems, whereby signaling  
information is transferred through...

Glossary
Issue  4  September 1995GL-15 
expansion control carrier
A carrier in a multicarrier cabinet that contains extra port circuit packs and a maintenance inter-
fac e. Also called ‘‘ex pansion control cabinet’’ in a single-carrier cabinet.
expansion interface (EI)
A port circuit pack in a port network (PN) that provides the interface between a PN’s time-division 
multiplex (TDM) bus and packet bus, and a fiber-optic link. The EI carries circuit-switched data, 
packet-switched data, network control,...

Glossary
GL-16Issue  4  September 1995 
fiber optics
A technology using materials that transmit ultrawideband electromagnetic light-frequency ranges 
for high-capacity carrier systems.
fixed
Fixed is a trunk allocation term. In the fixed allocation scheme, the time slots necessary to su pport 
a wideband  call are contiguous, and the first time slot is constrained to certain starting points.
flexible
Flexible is a trunk allo cation term. The flexible allocation scheme allows the time slots of a wide-
b...

Glossary
Issue  4  September 1995GL-17 
H0
An ISDN information transfer rate for 384 kb ps data defined by CCITT and ANSI standards.
H11
An ISDN information transfer rate for 1536 kbps data defined by CCITT and ANSI standards.
H12
An ISDN information transfer rate for 1920 kbps data defined by CCITT and ANSI standards.
Hertz (Hz)
A unit of frequency equal to one cycle per second.
high reliability system
A system having the following: two control carriers, duplic ate expansion interface (EI) circuit 
p a...

Glossary
GL-18Issue  4  September 1995 
Integrated Services Digital Network (ISDN)
A public or private network that provides end-to-end digital communications for all servi ces to 
which users have access by a limited set of standard multipurpose user-network interfaces 
d efine d  b y  the CCITT. Through internationally acc e pted standard interfaces, ISDN provides digi-
tal circuit-switched or packet-switched   communi cations within the network and links to other 
ISDNs to provide national and...

Glossary
Issue  4  September 1995GL-19 
internal measurements
Refers to those BCMS measurements that are made by the system. ACD measurements that are 
made external to the system (via External CMS) are referred to as external measurements.
in-use lamp
A red light on a multiappearance voice terminal that is illuminated to show which call appearance 
will be selected when the handset is lifted or which call appearance is active when a user is 
off-hook.
ISDN Gateway (IG)
A feature allowing integration of...

Glossary
GL-20Issue  4  September 1995 
local area network (LAN)
A networking arrangement desi gned for a limited geographical area. Generally, a LAN is limited 
in range to a maximum of 6.2 miles and provides high-speed carrier servic e with low error rates. 
Common configurations include daisy chain, star (including circuit-switched), ring, and bus.
logical link
The communications path between a processor and a basic rate interface (BRI) terminal.
loop-start trunk
A trunk on which, after establishing a...