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DEFINITY Enterprise Communications Server Release 6
Installation and Test for Multi-Carrier Cabinets
555-230-112
Issue 5
May 1998
Glossary and Abbreviations
Page GL-9
BTU
British Thermal Unit
buffer
1. In hardware, a circuit or component that isolates one electrical circuit from another. Typically, a
buffer holds data from one circuit or process until another circuit or process is ready to accept the
data.
2. In software, an area of memory that is used for temporary storage.
bus
A multiconductor electrical path used to transfer information over a common connection from any
of several sources to any of several destinations.
business communications terminal (BCT)
A digital data terminal used for business applications. A BCT can function via a data module as a
special-purpose terminal for services provided by a processor or as a terminal for data entry and
retrieval.
BX.25
A version of the CCITT X.25 protocol for data communications. BX.25 adds a fourth level to the
standard X.25 interface. This uppermost level combines levels 4, 5, and 6 of the ISO reference
model.
bypass tie trunks
A 1-way, outgoing tie trunk from a tandem switch to a main switch in an ETN. Bypass tie trunks,
provided in limited quantities, are used as a last-choice route when all trunks to another tandem
switch are busy. Bypass tie trunks are used only if all applicable intertandem trunks are busy.
byte
A sequence of (usually eight) bits processed together.
C
CACR
Cancellation of Authorization Code Request
cabinet
Housing for racks, shelves, or carriers that hold electronic equipment.
cable
Physical connection between two pieces of equipment (for example, data terminal and modem) or
between a piece of equipment and a termination field.
cable connector
A jack (female) or plug (male) on the end of a cable. A cable connector connects wires on a cable
to specific leads on telephone or data equipment.
CAG
Coverage answer group
call appearance
1. For the attendant console, six buttons, labeled a–f, used to originate, receive, and hold calls.
Two lights next to the button show the status of the call appearance.
2. For the voice terminal, a button labeled with an extension and used to place outgoing calls,
receive incoming calls, or hold calls. Two lights next to the button show the status of the call
appearance.