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 “Single-Line Voice Terminals.”
Appearance
See “Call Appearance.”
Asynchronous Data Transmission
A scheme for transmittingdata where each character is preceded by
a start bit and followed by a stop bit, thus permitting data elements
to occur at irregular intervals.This type transmission is
advantageous when transmission is not regular (characters typed at
a keyboard).
Asynchronous Data Unit (ADU)
A Data Communications Equipment (DCE) device
connection between RS-232C equipment and the
ports on the TN726 Data Line circuit pack.that allows direct
digital switch via
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							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 Announcement Devices
l External Alerting Devices (external alerts)
l Music-on-Hold Equipment
l Paging Equipment.
Auxiliary Trunk
A trunk circuit used to connect auxiliary equipment to the switch.
Only dictation and paging equipment may be connected via an
auxiliary trunk.
Bit (Binary Digit)
One unit of information in binary notation (having two possible states
or values, 0 or 1).
Bridge (Bridging)
The sharing of the same extension by two or more voice terminals.
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							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
appear.Calls may be received, originated, and held at an
appearance. System Access,Personal Lines, Direct Extension
Selection, and Pooled Facilities are examples of call appearances.
Software makes it seem to the terminal user that a line actually is
terminated at the button.
Call Appearance, Voice Terminal
A button labeled with an extension number or line number used to
place outgoing calls, receive incoming calls, or hold calls. Two
light-emitting diodes (LEDs) next to the button show the status of the
call appearance or status of the call.
CCS (Hundred Call Seconds)
A traffic-measuring unit that expresses the load of one or more
traffic-handling devices.A device used for 1 hour without
interruption represents a load of 36 CCS which equals 1 Erlang (see
“Erlang”).
Central Office
The location housing telephone switching equipment that provides
local telephone service and access to toll facilities for long-distance
calling.
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							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 restrictions.
Common Control Switching Arrangement (CCSA)
A private telecommunications network using dedicated trunks and a
shared switching center for interconnecting company locations.
Confirmation Tone
Three short bursts of tone followed by silence; indicates that the
feature has been activated, deactivated, or canceled.
Console
See Attendant Console.
Coverage Call
A call that is redirected from the called station to an alternate
answering position.
Coverage Path
The order in which calls are redirected to alternate answering
positions.
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							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 (DDC)
The extension number of a digital data endpoint.
Data Endpoint
Two general groups:
those having a DTE-type interface, which
encompasses almost all of the data terminal devices, and those
having a DCE interface, which are primarily modems. It should be
noted that within each category control interfaces may vary. Refer
to Analog Data Endpoint and Digital Data Endpoints for additional
information.
Data Module
A DCE device providing a standard interface between data
equipment and a TN726 Data Line CP port on the switch. Only ADU
Models Z3A1, Z3A2, Z3A4, and Z3A5 are supported.
Data Terminal Equipment (DTE)
DTE refers to a specific RS-232C connector termination designed to
connect directly to a DCE-type connection. Typically associated with
video display terminals, printers, and computers which either
originate or terminate a data transmission path.
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							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 Data
Units.
Digital Tape Unit (DTU)
RS-232C peripheral DTE used to store and reload system
translations.
Direct Extension Selector (DXS) Console
An option at the attendant console that allows an attendant direct
access to voice terminals by pressing a Group Select button and a
DXS button.
Direct Group Call (DGC)
An incoming call that arrives on a loop-start, ground-start, or tie
trunk and is routed to a predetermined group of stations (for
example, sales department, service department).
Direct Inward Dialing (DID)
A service whereby the called extension (station) number is
transmitted to a PBX by the central office (CO) and incoming calls
are routed directly to the called station, bypassing the attendant.
Dual-Tone Multifrequency (DTMF)
Industry terminology for touch-tone calling.
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							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 Call
A connection between a system user and a party on the public
telephone network or on a tie trunk. Sometimes referred to as an
outside call.
Facility (Physical)
A transmission channel to another switching system; to a Central
Office, for example. By application, examples are:
l CO Trunks
l FX Trunks
l WATS Trunks
l OCC Trunks
l Tie Trunks.
By technical type these include loop start, ground start, DID,
automatic ringdown, etc.These facilities may be accessed by their
facility access codes (FACs).
Facility Restriction Level (FRL)
A restriction parameter associated with ARS. Determines whether a
particular station can access a particular trunk.
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							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 (FNPA) Code
An area code other than the local area code. The FNPA code must
be dialed to call outside the local numbering plan area.
Ground Start Trunk
On outgoing calls, System 25 transmits a request for service to the
distant switching system by grounding the trunk ring lead. When the
distant system is ready to receive the digits of the called number,
that system grounds the trunk tip lead. When System 25 detects this
ground, it removes the ground from the ring lead and the trunk is
ready for service.
Home Numbering Plan Area (HNPA) Code
The local area code. Does not have to be dialed to call numbers
within the local numbering plan area.
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							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 requested.
Interface
A common boundary between two systems or pieces of equipment.
Internal Call
A connection between two stations within the system. Sometimes
called an inside or intercom call.
l-Use Lamp
A red lamp on a multiline voice terminal that lights 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.
Loop Start Trunk
Simplest type of central office (CO) trunk. Calls are originated by
providing a dc path between the tip and ring leads. The CO detects
the loop current thus drawn and returns dial tone. Incoming calls are
signaled by the CO placing an ac ringing voltage between the tip and
ring leads. [The port circuit pack (CP) detects this signal.]
Modem
A device that modulates and demodulates signals transmitted over a
communications path. Used to connect Data Terminal Equipment to
the system’s analog ports. The system (optionally) provides a 212A
compatible conversion resource.
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							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
Provided by the telephone company in two forms:
(1) RJ21X for trunk facilities other than tie trunks.
(2) RJ2GX for tie trunk facilities.
Number Plan Area (NPA)
The area code.
Off-Premises Station (OPS)
An arrangement provided by the local telephone company which
permits remote Terminal Equipment to operate as though it was
directly connected to the system. This tariffed service can be
provided only for FCC registered single-line voice terminals.
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