ATT System 25 Maintenance Manual

GLOSSARY
The following isa list of definitions of terms used in System 25
documentation.
Administer
To access and change the parameters associated with the services
or features of the system.
Analog Data Endpoint
Data endpoints connected to the system by (built-in or stand-alone)
modems.They do not requirethe use of data modules
(asynchronous data units) and are addressed like a voice terminal,
by Personal Dial Code (PDC). These endpoints connect to tip ring
circuit pack ports.
Analog Voice Terminals
See...

GLOSSARY
Attendant
The operator of the attendant console.
Attendant Console
l Direct Trunk Console:An electronic call-handling position with
pushbutton control.Used by attendants to answer and place calls
and to manage and monitor some system operations.
l Direct Extension Selector (DXS) Console: Provides the attendant with
a visual indication of the status of stations. Also allows the attendant
to conveniently extend incoming calls to stations.
Auxiliary Equipment
l Dictation Equipment
l Delay...

GLOSSARY
Buffer
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.
Bus
A multiconductor electrical path used to transfer information over a
common connection from any of several sources to any of several
destinations.
Bus, Time Division Multiplex
See “Time Division Multiplex Bus.”
Call Appearance
A button on a multiline voice terminal at which a call seems to...

GLOSSARY
Central Office Codes
The first three digits of a 7-digit public network telephone number.
These codes are numbered from 200 through 999 and are
sometimes referred to as NNXs.
Central Office Trunk
A telecommunications channel that provides access from the system
to the public network through the local central office (CO).
Channel
A communications path for transmitting voice and data.
Class of Service (COS)
Parameters used to define voice terminal, data, and trunk port
capabilities and...

GLOSSARY
Covering User
The person at an alternate answering position who answers a
redirected call.
Data Channel
A communications path between two points used to transmit digital
signals.
Data Communications Equipment (DCE)
Refers to a specific RS-232C interface connector configuration. DCE
devices are designed to interface directly (pin-for-pin) to Data
Terminal Equipment (DTE).The transmit and receive pins are
reversed from that of a DTE interface. A modem is an example of a
DCE device.
Data Dial Code...

GLOSSARY
Delay-Dial Tie Trunk
After a request for service (called a seizure) is detected on an
incoming trunk, the system sends a momentary signal followed by a
steady tone over the trunk. This informs the calling party that dialing
can start. This type of trunk allows dialing directly into the system;
that is, the digits are received as they are dialed.
Digital Data Endpoints
In System 25, digital data endpoints include any DTE or DCE with an
RS-232C interface to the switch connected via Asynchronous...

GLOSSARY
Emergency Transfer Unit (ETU)
Provides direct connection of designated Power Failure Transfer
(PFT) registered voice terminals to the CO during a power failure or
other service interruption.
Erlang
A traffic measuring unit that expresses the load of one or more
traffic-generating devices [36 CCS equals 1 erlang—see ‘‘CCS
(Hundred Call Seconds)”].
Extension Number
A 1- through 4-digit number assigned to each voice terminal and
data endpoint in the system. Also see “Personal Dial Code.”
External...

GLOSSARY
Fast Busy Tone
See ”ReorderTone.”
Feature
A specifically defined function or service provided by the system.
Feature Button
A labeled button on a voice terminal or attendant console
designating a specific feature.
Foreign Exchange (FX)
A central office other than the one providing local access to the
public telephone network.
Foreign Exchange Trunk
A telecommunications channel that directly connects the system to a
central office other than its local central office.
Foreign Numbering Plan Area...

GLOSSARY
Immediate-Start Tie Trunk
After establishing a connection with the distant switching system for
an outgoing call, the system waits a nominal 65 milliseconds before
sending the digits of the called number. This allows time for the
distant system to prepare to receive the digits. Similarly, on an
incoming call, the system has 65 milliseconds to prepare to receive
the digits.
Intercept Tone
On System 25, this tone is the same as Reorder Tone. Indicates a
dialing error or denial of the service...

GLOSSARY
Modem Pooling
Provides shared-use conversion resources that eliminate the need
for dedicated modems.
Multiline Voice Terminal
A terminal equipped with several call appearance buttons for the
same extension number. Allows the user to handle more than one
call at the same time.
Multiplexed
The simultaneous transmission of two or more signals over a
common transmission medium.
Network
An arrangement of inter- and/or intra-location circuits designed to
perform specific functions.
Network Interface...