Telephone exchange information and planning system A case study of Vastrapur...

Telephone exchange information and planning system A case study of Vastrapur telephone exchange


Vanikar Y.V., Patel M.N., Kharod K. P., Matieda I.C
Geomatics Systems Division, Geomatics Group
Signal Image Information Processing Area,
Space Applications Centre, Ahmedabad
Department of Telecommunications is providing services to about three lakhs and odd subscribers in Ahmedabad City and this demand will go on increasing with more and more people gaining awareness of the benefits of being connected telephonically. The Ahmedabad Telecom area is divided into thirteen telephone exchanges and a subscriber is attached to one of the several exchanges. The telecommunications services have been computerised since about a decade and all this information is maintained in tabular form. The spatial information is being maintained in carefully hand drawn maps which are of several levels/kinds and innumerable. Whenever any changes are to be made in the telephone cables like diverting a telephone cable to another nearby pillar or erecting a new pillar, a lot of time is wasted in drawing the new maps or updating the already drawn maps. The personnel of the telephone department also have to take into consideration the existing telephone facilities that have been laid down i.e. they have to have the tabular information alongside while planning such changes. Hence, a need has been felt to explore the possibility of transferring the map information in digital format and to design and develop a software package to provide query based access using the available technology of GIS; where the spatial and non-spatial data could reside under a common umbrella. This study will help in exploring if the telecommunications services could be made more efficient in terms of rendering services – existing and futuristic, and gaining more visibility to the planning issues faced by the telecommunications department with a view to increase the efficiency, which would ultimately lead to increase in the customer satisfaction.

In order to develop an approach, conceptualize the design and to examine the utility of the study it has been decided to consider Vastrapur Exchange Area, which is a suburb in western part of Ahmedabad as the pilot project area.

It is well understood that the personnel of Department of Telecommunications(DOT) need not be burdened with understanding the jargons and the intricacies of GIS technology. Hence, a user-friendly package is being designed and developed which will guide the technical personnel of DOT right from database creation, linking of spatial and non-spatial data, generating the required network coverage and querying different data to satisfy their management requirements. The customized package is being developed using Arc/Info GIS and Visual C++ on a windows NT platform. This paper provides the information on the design concepts and the functionality of the package.


The Vastrapur exchange area lies to extreme west in Ahmedabad Telephone Exchange area. At present the Vastrapur telephone Exchange caters service to more than 20,000 subscribers. Two main distribution frames (MDF) are situated at the Vastrapur telephone exchange. About 22 pairs of leading-in (LI) cables each having different capacities are laid down from the MDF in telephone exchange premises. Each primary cable from the MDF in the telephone exchange, extend to one or gets distributed in two or more pillars. The distribution cables originate from individual pillar and terminate into a number of distribution points (DPs). These DPs extend connections to individual subscribers. Thus a telephone call is received and sent through the network of MDF, primary cables, pillars, distributions cables, distribution points overhead cables to the subscriber as shown in Figure 1. Also it is mandatory to lay down the primary cables and pillars on public property only.

Considering the above given facts and considering the requirements it was worked out that the prime objective of this study would be:

  • better handling of the map and attribute data and faster updating of spatial information
  • estimate length and direction of cable network from one point to another point on the network for the existing cable network.
  • draw the route of a given lead-in cable and the associated pillars on the map.
  • optimize cable network along the roads and estimate the length of the cable to be laid down.
  • indicate number of working tags, waiting tags, utilized tags and percentage of filled tags in the pillars from time to time.
  • suggest new locations for erection of pillars for cable expansion
  • generate fault/performance reports for lead-in cables, pillars and distribution points.

Database Organization
The database consists of spatial and non-spatial component. The spatial component includes coverages like road, the locality map depicting the major localities of Vastrapur area to serve as reference coverage, primary cable coverage and Pillar location coverage. The non-spatial component consists of subscriber’s list( which includes detail of name, address, the associated pillar and the distribution point and his address in MDF), pillar utilization data from time to time (this is being updated every quarter by the telephone department), primary cable data with details on size, weight, tags etc. The spatial and non-spatial data have been appropriately linked to generate the required information.

The above mentioned data was received from the department of telecommunications. The maps are available at 1:8000 scale. [Recently, we have also received locality map at 1:2400 surveyed and digitised by M/S. Setu of Ahmedabad, which will be replaced by 1:8000 scale in near future]. These maps were digitized, corrected and topology built where required. The methodology of database creation has been represented as figure 2. In order to work out optimal planning of cables a cable network model and a road network model has been developed in GIS environment. The modules which have been used from the Arc/Info are mainly the ARCEDIT, ARCPLOT which includes the NETWORK module.

Telephone Exchange Information And Planning Systems (TEIPS)
The customised package TEIPS has been developed using the Arc/Info’s macro language (AML) for the GIS related operations and Visual C++ for developing the user’s interface. The idea for developing the front end in Visual C++ is its reusability even if the GIS is replaced by other GIS. The software design follows a modular approach. The customized package has a set of five major modules (figure 3) that perform a variety of functions like spatial and non-spatial database organization, editing of spatial features, generating network and routes and querying of associated information. While designing the above modules care has been taken not to mention terminology like points, line and polygon coverage. The telephone personnel will interact without getting to know the underlaying GIS jargons. The modules are as follows.

This module is the very first module a user has to interact. This module allows for creation of spatial and non-spatial data. The users are allowed to:

  1. create master map, locality map, road map, pillar location map, primary cable map using a digitizer or a mouse or keyboard
  2. edit an already existing map.
  3. import a map that has been created elsewhere in Arc/Info format.
  4. import a scanned map
  5. cleaning and building of coverages also happen in this module.
  6. creation of non-spatial table
  7. altering the structure of non -spatial table
  8. deleting a table.
  9. importing of non-spatial table from dbase format.
  10. cleaning and creation of topology of the coverages

The Network module provides all functionality pertaining to creation and maintainability of networks that includes bifurcating routes also. The following are the functionality provided :

  1. create a network for the entire map features
  2. update the network of an existing network. This is useful if any updating has been done after the network was created.
  3. create bifurcating routes
  4. delete a network/route

Information Generation/Presentation
This module answers most of the queriesthat the personnel of telecom department would like to ask and generate information on. At the outset as the cursor is moved over locations of different telephone exchanges a pop-up window gives details of telephone exchange like the number of levels, no of pillars, primary cables, geographical area, no of subscribes etc. The other functionality include:

  1. Active date : This pertains to the pillar status in the telephone exchange. The pillar status is updated once in a quarter. The pillar status gives details like the total tags available in the pillar, the working tags, waiting tags, utilized tags, percentage filled tags etc. The pillar status is displayed based on the active date selected by the user.
  2. Show: This menu queries details related to the network or route based information like generating :
    1. route based on a telephone number of the subscriber. Graphic display depicting the route from the telephone exchange to the associated pillar is shown on the terminal. Other information like the subscriber’s name, Address, the associated pillar number and the corresponding address in MDF is shown in a text window. Radio buttons are also provided if the user wants to find out the direction from the telephone exchange to the corresponding pillar location and for viewing the pillar boundary layout scanned map.
    2. Route based on a pillar number. Similar to the above case a graphic display depicting the route from the telephone exchange to queried pillar is shown. The detail given in text window is the utilization status of the pillar for the queried date. Radio button is given for directions of the route from telephone exchange to the pillar.
    3. Route based on LI number. Graphic display depicting the route of specified lead-in cables and associated pillar/pillars are depicted as shown as figure 4. This gives information as to how many pillars are attached to a pair of LI from the telephone exchange to the associated pillar.
    4. Route based on interactive pointing. Graphic display depicting the route between two or more points specified interactively is shown. This gives an idea to the telecom staff of the extensions they would like to do and how much of new cable would have to be laid to either divert the existing telephones to a new pillar or to give new connections to the subscribers in waiting.
      1. Save : saves the graphic display for printing.


      2. Report: Reports on subscriber and joints and ducts information for various LIs could be printed.


      3. Print: The saved graphic display will be printed in HPGL or plot files


Help: This menu guides a user to operate the customized package and provides all the instructions at every step.

Future development
This system is more of an information retrieval system as of today. An attempt to include the planning models will be made in future. Also as of today this is a single user system for which one requires the core Arc/Info system which is a expensive affair. It is being considered to workout some kind of client server kind of architecture where the investment on the client side will be much less so that only at the head office a full fledge GIS system will be required whereas the client side can still work with limited GIS functionality.

The conceptual framework has been worked out, implemented and is being demonstrated for this pilot area. On completion and acceptability of the approach and implementation, the same philosophy could be applied to other telephone exchanges under the Ahmedabad Telephone Exchange jurisdiction. This is a general case and in fact could be adopted to any telephone exchanges were the cabling is terrestrial.

The authors wish to thank Shri A.K.S. Gopalan, Director SAC for giving us an opportunity to work on this project. We are grateful Shri A.R. Dasgupta, Deputy Director, SIIPA, SAC and Shri Ashok Kumar, Principal GM, Ahmedabad Telecom during 1996 to have suggested to take up this project for GIS application. We also thank Shri S.R.Agrawal G.M.(West), Ahmedabad Telecom District and his staff to keep the interest alive. We are highly indebted to Ahmedabad Telecom District to provide us the required data and give us understanding of the working of the telecom machinery. This project would not have seen the present day progress without the efforts of Vasana Telephone Exchange staff Mrs. Sarla R. Sheth, Mr. N. M. Momin, Shri W.V.Christian and Shri S.D.Parmar in preparation of the data and data entry. We sincerely thank Shri R.K. Goel and Shri S.K. Pathan to extend their valued suggestions during the project reviews. We thank all our colleagues at SAC and the personnel from DOT who have taken so much pains every time to look at the software package and give their precious feed back.