ATT System 25 Maintenance Manual

							GLOSSARY
Out-Of-Building Station
Terminal Equipment directly connected to the system, but not
located in the same building as the common equipment. Special
arrangements are made to protect the system and its users from
lightning, power line crosses, etc.Only single-line and 7300H series
voice terminals may be so connected. (MET sets cannot be
connected as Out-of-Building stations.)
Paging Trunk
A telecommunications channel used to access a paging system.
Peripheral Equipment
Equipment connected to one of the RS-232C channels on the Call
Processor CP. Examples are the System Administration Terminal
(SAT), SMDR Output device such as a Printer or a Call Accounting
System, and Digital Tape Unit (DTU).
Personal Dial Code (PDC)
Voice terminal extension number.
Each system user is assigned a PDC and is allowed to “login” the
PDC at any voice terminal in the system as they move about the
premises. The PDC may be a 1-, 2-, 3-, or 4-digit number. There
are two types of PDCs:
l PDCs assigned to voice terminals—One is associated with each
voice terminal in the system.
l Floating—Assigned to visitors who will be moving about the
premises. Floating PDCs may be associated with the attendant
position or may be “logged in” by the user at any voice
terminal. Calls to the floating PDC will ring at the terminal
where “logged in.”
Pickup Group
A group of individuals who can answer any incoming call within the
group by dialing a code.
12-11 
						

							GLOSSARY
Port
An interface circuit between System 25 and associated trunks and
terminals. Specifically:
l Terminal port (station port)
l Facility port (trunk port)
l Auxiliary equipment port.
Private Branch Exchange
A switching system that provides switched communications access
among its terminals and facilities (for example, System 25).
Private Network
A network used exclusively for handling the telecommunications
needs of a particular customer.
Private Network Office Code (RNX)
The first three digits of a 7-digit private network number. These
codes are numbered 220 through 999, excluding any codes that have
a 0 or 1 as the second digit.
Protocol
A set of conventions or rules governing the format and timing of
message exchanges to control data movement and correction of
errors.
Public Network
The network that can be openly accessed by all customers for local
or long-distance calling.
Queue
An ordered sequence of tasks to be processed.
Queuing
The process of holding calls in order of their arrival to await
connection to an attendant, to a DGC group, or to an outgoing trunk.
Calls are automatically connected in first-in, first-out sequence.
12-12 
						

							GLOSSARY
Random Access Memory (RAM)
A storage arrangement whereby information can be retrieved at a
speed independent of the location of the stored information.
Read Only Memory (ROM)
A storage
arrangementprimarily for information retrieval
applications.
Recall Dial Tone
Three short bursts of tone (confirmation tone) followed by steady dial
tone; indicates the system has completed some action (such as
holding a call) and is ready to accept dialing.
Redirection Criteria
The information administered for each voice terminal that determines
when an incoming call is redirected to coverage.
Reorder Tone
A tone repeated 120 times a minute; indicates that at least one of the
facilities, such as a trunk or a digit transmitter, required for the call is
not available. Also called Fast Busy Tone.
Single-Line Voice Terminals
Single-line voice terminals served by a Tip Ring Line or Analog Line
circuit pack (2500 series and 7101A voice terminals or industry
standard Dual-Tone Multifrequency equivalent).
Software
A set of computer programs that accomplishes one or more tasks.
12-13 
						

							GLOSSARY
Station
A place where terminal equipment is located or sometimes the
terminal equipment itself. Each voice terminal (station) is assigned a
station (extension) number.Users of the terminal are sometimes
referred to as station users. Reference to the extension number is
sometimes in the form PDC (PersonaI Dial Code) rather than station
number. PDCs may be “logged in” at other stations. In most
circumstances,PDCs and station numbers may be used
interchangeably.Analogously, data stations are assigned DDCs
(Data Dial Codes).
Station Interconnect Panel (SIP)
The station cross-connect field.
Station Message Detail Recording (SMDR)
Data output by System 25 that provides a record of each incoming
and outgoing external call.
Status LED (lamp)
A green LED or lamp that shows the status of a call appearance or a
feature button by the state of the lamp (lighted, flashing, fluttering,
broken flutter, or dark).
Switch
The software-controlled communications processor complex that
interprets dialing pulses/tones/keyboard characters and makes the
proper interconnections both within the system and outside the
system. The switch itself consists of a digital computer, software,
storage device (memory), and associated circuit packs and special
hardware necessary to perform the actual connections.
Switchhook
The button(s) on a voice terminal located under the receiver. A user
typically goes “off-hook” to place or answer a call by picking up the
receiver and goes “on-hook” (hangs up) to end a call.
12-14 
						

							GLOSSARY
System Administration Terminal (SAT)
RS-232C DTE peripheral equipment used to enter and change
system translations.
System Administrator
A person responsible for specifying and administering features and
services for the system.
System Restore
A process that allows stored data to be written from a tape into the
system memory (normally after a cold start).
Terminal Equipment
Equipment used to change information (sound, keystrokes) into an
electrical signal compatible with System 25’s port circuits. (Voice
and data terminals are the two primary types.)
Tie Trunk
A telecommunications channel that directly connects two private
switching systems.
Time Division Multiplex Bus
A special bus that is time-shared by preallocating short time slots to
each transmitter on a regular basis. In a PBX, all port circuits are
connected to the time division multiplex bus permitting any port to
send a signal to any other port.
Tone Ringer
A device with a speaker, used in electronic voice terminals to alert
the user.
Translations
Specific information assigned to a terminal or to the system and
customized for the user. Translations are entered and changed via
the SAT.
12-15 
						

							GLOSSARY
Trunk
A telecommunications channel between two switching systems.
Trunk Access Equipment (TAE)
The cross-connect field for central office (CO)/network facilities.
Trunk Group
Telecommunications channels assigned as a group for certain
functions.
Trunk Port
The hardware (circuit pack) providing an interface between the
system and central office (CO)/network trunks.
Unit Load
A measurement used to evaluate a System 25 cabinet’s power load
capacity. Each System 25 cabinet can handle 80 unit loads of 48-
volt power. One unit load equals 44mA.
Voice Terminal
A single-line or multiline voice instrument (that is, telephone). See
“Terminal Equipment.”
Wide Area Telecommunications Service (WATS)
A service that allows calls to a certain area or areas for a flat-rate
charge based on expected usage.
Wink-Start Tie Trunk
After establishing a connection with a distant switching system for
an outgoing call, the system waits for a momentary signal (wink)
before sending the digits of the called number. Similarly, on an
incoming call, the system sends the wink signal when ready to
receive digits.
12-16 
						

							GLOSSARY
Write Operation
The process of putting information onto a storage medium such as
magnetic tape.
800 Service
A service that allows incoming calls from a certain area or areas to
an assigned number for a flat-rate charge based on usage.
12-17 
						

							INDEX
A
Abbreviations 11-1
Acronyms 11-1
Address Leads
Circuit Pack 3-28
Administration Manual 10-1
Administration Manual, Advanced 10-2
Administrative Software 4-1
Alarm Indicators 2-3
Alarms 2-2
Allocation
Memory 4-2
Analog Line (TN742) 3-41
ATL Line (ZTN79) 3-35
Automatic Maintenance Tests 5-5
Auxiliary Trunk (TN763) 3-49
B
Backplane Trouble 8-18
Bus
TDM 3-16, 4-5
C
Cabinet Trouble 8-18
Call Description 4-7
Call Processor Circuit Pack 3-10, 4-4
Circuit Pack Address Leads 3-28
Circuit Pack LEDs
Interpreting 8-8
Circuit Pack Trouble 8-11
Circuit Packs
Analog Line (TN742) 3-41
ATL Line (ZTN79) 3-35Circuit Packs (Continued)
Auxiliary Trunk (TN763) 3-49
Call Processor 3-10, 4-4
Circuit Pack 3-14
Data Line (TN726) 3-37
DID Trunk (TN753) 3-43
Ground Start Trunk (ZTN76) 3-29
Loop Start Trunk (ZTN77) 3-31
Memory 4-4
MET Line (TN735) 3-39
Pooled Modem (TN758) 3-56
Port 4-5
Replacement 8-1
Reseating 8-1
Service Circuit (ZTN85) 3-51
System Resources 3-51
Tie Trunk (TN760B) 3-45
Tip Ring Line (ZTN78) 3-33
Tone Detector (TN748) 3-54
Circuitry
Common Control 3-10
Circuits
Port 3-21
Clearing Specific System Troubles 8-9
Clearing System-Detected Troubles 8-1
Clearing User-Reported Troubles 9-1
Common Control 3-8, 3-10
and Switching Network 3-8
Problems 5-4
Trouble 8-9
Connector Pin Assignments 8-24
Constraints
Real-Time 4-3
13-1 
						

							INDEX
Data Line
(TN726) 3-37
Troubles 9-11
Dictionary
Error Log 6-5
DID Trunk (TN753) 3-43
Digital Switch 3-3
Digital Tape Unit 3-8
Operation 7-1
Documentation 10-1
DTU 3-8
Operation 7-1
Troubles 9-1
DFailures
Total 5-3
Fan Assembly Trouble 8-17
Frontplane Ribbon Connector Trouble -
8-12
G
General Maintenance Information 2-1
Glossary 12-1
Ground Start Trunk (ZTN76) 3-29
H
Hardware
Overview 3-1
E
IEmergency Transfer 2-3
Unit 3-7
Unit Trouble 8-26
Equipment
DTU 3-8
ETU 3-7
Terminal 3-7
Test 1-3
Trunk Access 3-5
Wiring 3-7
Error Log 2-2, 6-1
Access 6-3
Consulting 8-1
Dictionary 6-5
Errors 2-2
ETU Trouble 8-26Implementation Manual 10-2
Indicators
Alarm and Status 2-3
Installation and Test Manual 10-2
Introduction to AT&T System 25 10-2
L
LEDs
Circuit Packs 8-8
Log
Error 2-2, 6-1
Loop Start Trunk (ZTN77) 3-31
M
F
Failure
Complete System 8-9
Maintenance 5-5Maintenance Failure 5-5
Maintenance Information
General 2-1
Maintenance Manual 10-3
13-2 
						

							INDEX
Maintenance Objects 2-1
Maintenance Software 4-2
Maintenance Strategy 5-1
Maintenance Tests 2-5
Automatic 5-5
Memory Allocation 4-2
Memory Bus 3-10
Memory Circuit Pack 3-14
Memory Circuit Packs 4-4
MET Line (TN735) 3-39
Multiple Troubles 9-12
N
New Capabilities Manual 10-3
NPEs (Network Processing Element) -
3-28
O
Overheating Trouble 8-18
P
Panel
617A 3-3
Partitioning
Software 4-3
Pin Assignments
Connector 8-24
Planning Manual 10-3
Pooled Modem (TN758) 3-56
Port Circuit Options
For Stations 9-9
For Trunks 9-9
Port Circuit Packs 4-5
Port Circuits 3-21
Port Problems 5-3
Power Failure Transfer 2-3Power Supply
Protection 8-16
Replacement 8-16
Trouble 8-12
Power
Removing 8-3
Restoring 8-3
Precautions 1-4
Problems
Common Control 5-4
Port 5-3
Station 5-4
Trunk 5-4
Wiring 5-4
Procedures
General 5-3
Protection
Power Supply8-16
R
Real-Time Constraints 4-3
Receiver Test
Touch-Tone 9-3
Reference Documentation 10-1
Reference Manual 10-4
Replacement
Power Supply 8-16
S
SAT 2-4
Troubles 9-1
Service Circuit (ZTN85) 3-51
SIP 3-3
SMDR Troubles 9-1
Software
Administrative 4-1
General 4-1
Maintenance 4-2
13-3