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Subscriber Line Maintenance, Trunk Line


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Chapter V

OPERATION AND MAINTENANCE

5.1 Robot Information

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5.2 Switchboard management operations

5.3 Switchboard maintenance

Subscriber Line Maintenance, Trunk Line


5.1 Robot Information

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5.1.1 Overview of ManMachine information

In SPC switchboards that use processors to control the switchboard, peripheral devices for man-machine exchange are connected to the switchboard. Thanks to these devices, operators and maintenance staff can exchange information with the switchboard in Man Machine Language. Through this language, operators can manage information, process billing data, and perform system administration and operation requirements. System operation can be performed on-site or at the Operating Maintenance Center.

Robot language includes commands (Input), output messages (Output) and control messages.

Switchboard

control tasks, and how tasks such as testing and communicating with the system are performed. MML is the only tool for communication between people and the system. It needs to be designed for maximum efficiency and effectiveness.

OMC

Output (Screen, Printer, ...)

Input (Keyboard, mouse, communication commands...)

Figure 5.1 Structure of human-machine communication system

5.1.1.1 Structure of maintenance operation center


CC

OMC

OIC

MMI

VDU

PRT

DKU MTU STR

OAM

Figure 5.2 Structure of maintenance operations center

In there:

CC Center Control Central Control

OMC Operating Maintenance Center OMC Operating Maintenance Center

OIC Output / Input Controller Input / Output Controller

MMI Man Machine Interface

VDU Visual Display Unit

Chapter 5. Operation and maintenance

PRT Printer Printer

DKU Disk Unit Hard Disk Drive Unit

MTU Magnetic Tape Unit

STR Streamer Digital Data Tape Device Block

OAM Operating & Administrator Maintenance

* Functions of OMC: includes 3 main functions:

Management function: performs data storage of the system. To know the status of the object to be managed and the changes of the components in the system.

Monitoring function: Monitor all system activities to confirm whether the service to be provided is acceptable by testing.

Maintenance function: Includes tasks and functions to ensure the system works best under current conditions.

5.1.1.2 Characteristics of robot language

Based on a common language, usually English.

Easy to learn and easy to use to input commands and translate messages out

Contains full operational control commands to ensure system operation, maintenance, installation...

Open architecture to add new functionality without affecting existing

The command code will be function oriented (1 command per function).

Provides facilities for creating, deleting, and stopping active commands.

The word set used is the CCITT recommended Alphabetic character set.

5.1.2 Structure of Human-Machine Language

5.1.2.1 Command syntax

It is a set of rules for constructing commands in a grammatically correct language, it defines word sets, cipher keys, dividers and boundaries to make the written sentence clear.

* Basic components in syntax.

Identifier set: Is a set of letters starting from a group of letters, usually the initial information related to the command code and action of the job to be manipulated.

Example: DISSLNINFO:DN

Symbol name: Is a string of characters.

Counting numbers: Represented in different bases such as base 10, base 16.

Separator: Colon (:)

Indicator: the end of each command is a semicolon (;)

* Each command has a mandatory part and an optional parameter part.

Command code: To define the function to be performed, the actions to be performed on the system.

Parameters: After the command code is the parameter block.

Command code and parameter block are separated by a comma (:)

A command is terminated by a semicolon (;)

A parameter block consists of one or more parameters, the parameters are separated by the symbol (,)

Each parameter has a parameter name and parameter value separated by an equal sign (=).

* The format of a command and the structure of the command parameter block are described as follows.



Command code

,

:

=

;

Parameter block

Parameter name

Value


Some examples Example 1:

Figure 5.3 General command structure

Parameter Block Separator

REGSSVC:DN=850000,SSVC=ABS ;


Command end mark


Value of parameter Parameter


Example 2:

Command code


Parameter block

Cre Subd n=850075 el=000300317

2nd parameter Value of the parameter

First parameter Command code

* Types of newsletters

From SPC electronic switchboard systems, there are generally 4 types of messages output.

Command identification message (instruction): This message includes command number, time, date and communication device characteristics, this message is used to store the content of the

Chapter 5. Operation and maintenance

command has been issued.

Command response message (instruction): Includes information confirming the command initiation request and the command result.

System messages: These are system messages that automatically indicate events in system operations, or data and normal working status of important system function blocks. In addition, messages about warning status are also automatically issued.

Error message: The system will output an incorrect message when an incorrect command is entered into the system.

5.2 Switchboard management operations

5.2.1 Operation of switchboard equipment

Switchboard operation depends on the following factors:

Data stored in the switchboard

The program is stored in the processor.

Working status of hardware devices: such as distinguishing working and non-working status, status for testing.

Managing switchboard equipment means converting, setting up or deleting switchboard data.

For example, changing the outgoing trunk to a 2-way trunk, changing the service for the subscriber...

5.2.2 Subscriber line management

Including creating new subscriber numbers, converting subscriber lines, changing subscriber services, and setting up inactive subscribers.

Create new subscriber line.

Creating a new subscriber line requires entering an operation command into the switchboard system, which establishes a connection between the reserved directory number (DN) and the unallocated equipment address number (EN) with the appropriate attribute, distributing the billing set to the subscriber.

Move a subscription.

It involves changing the EN number assigned to the subscriber but leaving the DN, attributes and billing data unchanged, it is used for technical operations such as balancing voice traffic between circuits in different departments and interconnected parts of the switching network.

Change service for subscribers

Subscriber data can be changed by appropriate command according to DN and EN. Line service outage (suspension of subscriber operation)

When it is necessary to put the line out of service, it can be done by 2

way.

Service interruption (compression) includes: Opening the connection between EN and DN. Immediately

EN is available for other DNs. All calls to DN are transferred to the operator or the pre-recorded message of the subscriber's attributes is deleted from its file.

Out of service (delete): After deletion DN and EN become available for service again.

At the time of execution (compression) and (deletion) the content of the meter assigned to the line is output on the OMT.

5.2.3 Trunk line management

In the switchboard, the trunk data is stored in the switchboard memory as separate files. This file includes addresses obtained from local subscribers or incoming trunk lines. The trunk files define the trunk lines associated with the status of the trunks of the trunk group such as: Outgoing trunk, incoming trunk, 2-way depending on the type of signaling.

In the switchboard, the operator can redefine or change one or all of these functions by robot command.

5.2.4 System management

5.2.4.1 Fee data management

There are two sets of information stored in the fare file.

Data to calculate the cost of each call such as: Rate, area code... This data is provided to the call processing program in the form of a rate code, after analyzing the predetermined digits.

Billing content of each subscriber: Each subscriber has a separate billing set defined in the switchboard memory to record billing data for calls of this subscriber. Normally the operator cannot change the content in the billing set.

Normally, billing is done separately at the central computer used by the switchboards. To do this, the contents of the meter are periodically copied to a peripheral device suitable for the computer, such as a magnetic tape, or transmitted directly via the data line. The computer will bill each subscriber line based on the difference between the current and previous readings of the billing machine. In case of billing by item, the switchboard immediately records all the necessary information for each call, such as: Address of the called subscriber, call time... and then transfers this message to a suitable device when the call is terminated.

In addition, the content of the billing set is automatically printed out each time the operator creates a line, changes the DN, or temporarily suspends the operation of a number of subscribers.

5.2.4.2 Monitoring voice traffic and load

In SPC switching systems: Call monitoring and traffic measurement functions are fully integrated with the switching system in the switchboard, they are performed by the call processing program and more specialized voice test programs. They have the advantage of organizing frequent testing, monitoring the operation in a wider switchboard, and processing voice and updating results more reliably. On the other hand, the voice monitoring system outputs messages in a form that can be directly processed, enabling the operator to decide on timely and appropriate operational responses.

Chapter 5. Operation and maintenance

traffic balancing for subscriber switching blocks and trunk groups.

Monitoring modes: Depends on the object, and there are 2 types of monitoring

Regular monitoring: This monitoring method is to monitor the quality

Regular monitoring of services and traffic load in devices. Monitoring work is performed within the entire switchboard such as measuring the total number of outgoing and incoming calls, displaying basic parameters when the allowable values ​​exceed the limit, an alert will be generated.

These monitoring tasks are performed automatically, and the operator can change how the results are displayed, such as defining which figures to display, requesting that the figures be transferred to tape, or setting alarm trigger thresholds for any parameter.

Real-time monitoring: Monitoring involves some hardware components of the PBX system such as subscriber lines, trunks, and switching elements. The data collected is often processed by a computer to optimize the PBX's resource usage, to locate problems in trunks, or to evaluate changes in the network.

These monitoring commands are initiated by the operator and define the parameters that need to be monitored, the list of parameters can be created, modified, looked up and canceled through the operation command, the operator can perform automatic test measurements.

At specific intervals, the data is processed in the switchboard and the processing results are displayed for use by the manager or transferred to the appropriate storage device for sending to the computing center for processing.

When the switchboard is under high load, the instant monitoring work is stopped but does not affect the regular monitoring work.

5.3 Switchboard maintenance

Maintenance aims to maintain the stable operation of the switchboard to ensure continuous service provision to customers. Maintenance work is classified as follows:

* Regular maintenance (repair):

The task of the SPC switchboard security program is to detect errors in the switchboard hardware and software. When an error occurs, the central controller will trigger warning messages.

Thus regular maintenance is performed after a fault is detected in the system. The purpose of this method is to restore the normal state to perform the required function.

Maintenance does not require frequent system checks (less maintenance activities are required) but results in unstable service quality.

* Periodic maintenance:

Routine maintenance involves a series of routine tasks to check any parts that are likely to be sources of failure and repair them before they fail. This method requires a large amount of work to be done.

* Control maintenance:

The development of today's equipment provides new methods of maintenance, the system can immediately report information related to the existence of abnormal and irregular controls.

Periodic test measurements can be replaced by methods of continuous monitoring of system functions and measures to check the continuity of operation of equipment and provide warning signals to the operator when the service quality falls below a pre-set limit.

5.3.1 Maintenance of subscriber lines and trunk lines

5.3.1.1 Subscriber line maintenance

Includes testing of a subscriber line or group of subscriber lines and related equipment using human-machine commands. Testing of subscriber lines and telephones is divided into four parts:

* Subscriber line monitoring.

When a subscriber line is in an abnormal state, it is detected by the call processing software and the subscriber line is isolated from the switchboard (Lockout) the subscriber line.

The system periodically checks the status of all lines. An alert is generated from the periodic line check system when the line is locked out beyond the threshold for the entire switchboard or a certain line connection.

The alarm threshold and time between checks can be changed by command from the operator, which provides indication to the cause and location of the fault.

* Periodic testing to detect and identify faulty lines.

Periodic testing is initiated by the operator's command, testing can be initiated immediately after a period of storage of information about the faulty line and the line that has not been tested because it is busy is printed out on request from the operator's command. The operator can enter a test order for all lines during the night and have the results the next morning.

* The operator is assisted in testing the subscriber line to determine the source and cause of the line failure. The operator uses the system control command to perform the test as follows:

Measure open circuit on the line.

+ Measure AC voltage between T and ground

+ Measure AC voltage between R and ground

+ Measure DC voltage between T and ground

+ Measure DC voltage between R and ground

+ Measure the insulation impedance Z between T and ground

+ Measure the insulation impedance Z between R and ground

+ Measure the insulation impedance Z between T and R

Measure loop resistance on the line.

+ Loop Current

Chapter 5. Operation and maintenance

+ Loop Resistor

Dial-up telephone measurement

+ On/off time for each dial pulse.

+ Number of pulses received for a digit to be dialed.

Measure the phone press key

+ Frequency and level for digits.

+ Test subscriber phone

By performing simple tests at the subscriber's machine independently of the workload in the switchboard, or after repairing the line or telephone, it is possible to check:

+ Signal on the line.

+ Line insulation resistance.

+ Loop current.

+ Transmit bell current, adjust bell.

5.3.1.2 Trunk line maintenance

In SPC switchboards trunk data is stored in switchboard memory as separate files in the form of trunk profiles, which define the type, and group of trunk lines (Outgoing trunk, Incoming trunk, 2-way trunk) corresponding to the associated signaling type.

When a problem occurs or after a certain period of time, maintenance is necessary. When defects occur with the modules, the system will output warning messages. If the system cannot fix it itself, the operator must

proceed

through human-machine interface commands. Thanks to

communication commands

The robot can change the trunk structure.

Trunk testing can also be performed automatically and the results are output in the form of messages. However, automatic testing does not provide enough information for diagnosis, to restore normal operation of the faulty trunk lines. Therefore, manual testing equipment is required, which is often used for space SPC switchboards.

5.3.2 Maintenance of switching network, control system

5.3.2.1 Switching network maintenance

Work includes: Performing call testing, call monitoring, testing switches, locating faults in the switching network.

5.3.2.2 Control system maintenance

In switchboards, the automatic diagnostic program is responsible for detecting errors in modules and units. Execute this program to identify the functional unit or printed circuit board that has a problem.

The control system determines all operations of the switchboard, so the processors are equipped with a pair of hot standby (ACT/SBY) operating units. When a hardware failure occurs, the system will trigger an alarm. The operator uses commands to locate the failed module and replace it with the same type.

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