Indian
telephones
The beginning of voice
on wires:
28th January 1882, is a Red Letter Day in the history of
Telephones in India Calcutta ,
Madras, and Bombay Calcutta Calcutta
and Howrah through a cable laid beneath the
floating Howrah Bridge
The independent India Bombay , Calcutta , Delhi, and Madras
The railway control circuits were using the phone system for
trains’ movement.
It was still
a manual switching system in which every call is to be put through manually.
Gradually the system spread to state capitals and the district headquarters.
Primitive
communication system
A small
telephone exchange was opened in a district headquarter to start with. It was
placed near the market area, or some suitable place centrally located in the
town. Very few open wires served the main offices like the post office, polish
station, administrative offices and business houses, and some VIPs
connections. All connections taken together were probably less than 50[DELs]
direct exchange lines.
The manual call switching board [switch board] was simple with
indicator lamps to indicate the condition of phone lines by glowing small line
lamps. Lines were terminated on line terminals [hole-like jacks]. A line lamp
and associated line jack were the terminals of subscribers’ lines. To interconnect the callers to called subscribers [subs], a pair of connecting cords
were used.
The telephone operator has to respond to the demand of the
calling sub, answering the calling sub by inserting a cord into a line jack.
Ascertain the called number and connect to the called line and give a manual
ring to the called sub so that he lifts the handset; thus the connection is
established between the caller and the called numbers.
This was a simple manual exchange; the power supply was
managed centrally at the exchange itself and it was called CBNM [central
battery nonmultiple] exchange system.
Initial exchanges for telephony were of this nature, throughout the nation in India
Each subscriber was charged a monthly rent of Rupees 50/
towards the service given. The local calls were free of cast for the entire month.
Trunk circuits were established connecting with adjacent
district headquarters and taluk headquarters. Some large villages were also
connected with PCOs. Open wire lines [of tubular iron poles] were used. To
construct open wire lines and to maintain these lines in working order; a
separate staff called the line staff was recruited on a permanent basis. They
were called linemen; line inspectors etc. The switching apparatus was maintained
by a trained technician.
Multiple operators were used for rotational round-the-clock
duties. A senior man among them has to supervise the operational activity; and
manage the overall system.
The operator has to handle local calls, trunk calls,
book the ticket, for trunk calls and establish trunk calls and charge the calls
by noting the time of call connected and call disconnected.
These trunk calls (established) tickets were to be dispatched
to the revenue accounting office in the divisional office, where the Divisional
engineer’s office was established.
On the engineering side Divisional Engineer’s office, the Sub-divisional Engineer’s office, and the junior engineers’ office were established to
manage the technical affairs of the working system.
The background:
1837-telegraph
1864-existence of radio waves
1875-invention of telephone
1897-strowger exchange
1901-transmission of radio signals
1904-vaccum tube diode
1918-super heterodyne radio receiver
1948-mathematical theory of digital
communication
1948-invention of transistor
1955-proposal of satellite
communication
1958-silicon integrated circuit
1962-telstar satellite-bell lab
1966-use of fiber as a dielectric
waveguide
1971-pocket switching theory
Bidar being the district headquarters
had also a telephone system. In 1974 there were about 300 telephone lines in
Bidar town. The primitive system of local telephone lines was, all overhead
iron wires hanging along the local roads on tubular posts along the streets.
They were terminated on a manual switchboard. The manual switching of local
calls and trunk calls was done by telephone operators (TOs). Telephony was a
new flourishing business undertaken by the communication ministry and the
department was known as the Posts and Telegraphs (P&T) department.
Talented taught
students either of SSLC /PUC or of degree were regularly inducted or absorbed
in the system, to cope up with the growth of telecommunication service.
I was a 1973 science graduate (B.Sc.) and I was inducted as
TO in 1974. The Gulbarga division had four
districts covering Bellary , Raichir, Gulbarga, Gulbarga
Telephone
being the fastest method of communication was established in cities and towns.
The growth and modernization were slow.
Trunk lines
were constructed by erecting tubular posts along the state highways and other
road networks. The Indian railways used the service of telecom for trains’
movement. The trains' control and block lines were maintained by P&T. The
engineering supervisors, technicians, sub-inspectors ‘and linemen were the
people to construct and maintain the trunk lines. Two separate parallel
conducting wires which enable the path for the speech current to pass through
them were called trunk circuits. All these local lines and trunk lines were
terminated on manual switchboards and were handled by TOs.
Normally all taluka headquarters were connected to the
district headquarters by trunk circuits. And Bhalki was one such taluka in
Bidar district. There was a trunk line between Bhalki and Bidar along the
railway route. This route was further extended to Kamalnagar, Aurad, and Santapur. Some villages were directly terminated to the board and these lines
were known as PCOs (public call offices). A post office of the village houses a
phone instrument and the postmaster keeps the call records. There were about
70 working lines at the Bhalki telephone exchange. There were five telephone operators
to handle the telephone traffic of the town. One of them would be the head operator. He was
supposed to keep all the records of calls established and dispatch the tickets
to the divisional office for the calculation of call charges on individual lines. The
exchange system was very simple at Bhalki. A CB non-multiple board, a small MDF,
a battery room, and a carrier system of 1+3 type, were housed in a rented building. The external plant was, a bit of cable laid up to the Gunj main circle and local
lines feeding the shops. The engineering supervisor groups Bidar was in
charge of the system.
The customers
who used these services were billed monthly and if the bill is not paid, the
line was disconnected temporarily to press the party to pay the dues. The
revenue collection was thus regular and prompt. But the main problem was the
manual-working, especially during night hours, human nature is to sleep but
they were made to work like machines and they did not.
These early
telephone lines were of open wire type. The iron wires (galvanized) were drawn
right from the switching office to the subscribers’ premises, along the streets.
The trunk lines were going along the roads and they were exposed to wind
currents, the rains, and the night colds and mid-day heat of summer. There was
ware and tare. If the line is loose or the span length from pole to pole is
kept long, the wires got contact with each other due to wind disturbances, and
the line is short-circuited and hence dead. Sometimes there will be a break of
conductors and supporting posts slanting due to heavy rains. These were to be attended
promptly to restore the telephone services. Telegraph lines were also working
between post offices. A written message was generated known as a telegram and
sent to the concerned party.
This simple
system of connecting people manually by building circuits by operators from
place to place as a cascade was a well-established practice of manual
switching. Suppose that a subscriber at Bhalki wants to communicate with a person at
Gangavathi the call is to be routed through Bidar-Gulbarga-Raichur and then to
Gangavathi, the terminal destination of the called party. Since there were limited
circuits between towns, there used to be delay to establish a call. There will
be a lot of waiting time for a call to mature. The average waiting will be more than
one hour for any trunk call. And there was no substitute or alternate method to
that of calling a person in need. The marketing people, the businessmen the
executives were badly in need of telephone services.
A letter
takes 4 days, a telegram takes 24 hours, and a trunk call takes 2 hours, to
communicate. A trunk call is a two-way speaking system and no such facility can be had by other
means of communication. Thus it was of immense use to a business to happen
between two parties placed far away.
But the
service was not steady and there used to be interruptions again and again due
to the lines going out of order. Physical lines running kilometers and being exposed
to an open environment, caused a lot of inconvenience and the first party to face
the angry customer was the on-duty telephone operator.
A technique
to increase the trunk line capacity was developed by building carrier systems
on physical lines. The first one such system was a three-channel carrier
system. The advent of electronic circuitry in its primitive stage gave rise to
these speech carriers working in addition to the physical lines. That is if there
existed a physical line between two places, it was possible to increase the
circuits to a 1+3 system of trunks. This increased the availability of circuits
between two stations and call waiting time was reduced to 50%. This was a milestone in manual telephony.
Later on, automatic local exchange switches of Strowger technology were introduced in
towns and district places. This reduced the burden of connecting local calls
manually. The customer on hearing the dial tone has to dial the required number
himself. This automatic system was built on the electro-magnetic principle and uni-selectors
and two motion selectors were involved in the process of switching a local call.
To monitor the working of these selectors, technicians were employed. They used
to rectify the faulty switches. Here again, there was a problem of wrong
switching due to the switch going faulty. Wrong switching added to the revenue bill
of the customer and a cause of dispute.
Once the
internal system is made automatic, the customer has to dial the local number
himself. Thus the burden of the operator is reduced to a considerable extent. He has
to concentrate on trunk booking, answering incoming trunk lines to receive incoming calls from other stations, and to put-through the booked calls. Unmanned
small auto exchanges of lesser capacity were terminated on these trunk boards
to put through calls originating from those exchanges.
At district
head quarts, there was larger trunk traffics. Therefore, the numbers of boards
were more and the trunk lines were available as multiples at many boards. The
boards were called positions. At metros, there were still more positions and
hundreds of operators were working continuously round-the-clock. The duty hours
of an operator were normally 8 hours. They were coming to duty on shifts. This
was the system of manually switching calls.
Bulk of
trunk routes was needed to handle the growing traffic between metros. The
coaxial cables were laid between the major metros. Later when electronic
integrated circuits were developed, new microwave systems started appearing in
the field to build wireless trunk routes. The microwave towers were erected at
about a distance of 50km span length. Repeaters were installed at such locations
and the station was maintained with batteries and engine alternators.
Between1980-85, most of the metros were connected by microwaves. This technical
up-gradation gave rise to the availability of plenty of trunk lines between cities.
Now, the local and trunk were automatic and subscriber trunk dialing was
introduced between many cities. Thus the need for the operator is slowly eliminated
from the system. The operators were surplus and they were used for
miscellaneous works. The technical manpower was increased to maintain the new
systems. During Rajeev Gandhi as prime minister of India ,
one Mr.Shyam Pitroda came to India
Thus the communication network grew and works were
specialized and a separate internal wing was dedicated to maintain the major
trunk routes. Similar to railway zones, telecom regions were established to
handle the system effectively.
All such
things happened but most of the village population remained out of this
facility. The demand was building up and the service was not available to
villages. About 50% of the villages were not having communication links. If
there are PCOs, they were not maintained as desired due to technical reasons.
Efforts were made to install VPTs. But they did not serve the real purpose.
Meanwhile, optic fiber cables were developed and being inducted into the system.
These simple optic fibers were having a very large capacity to
increase the channels just by replacing the end units of trunk routers. They
were cost-effective and more stable and most of the microwaves were replaced by
OFC cables. In metros, multi-exchange cables, called junction cables were
replaced by OFC cables. Also, interior towns in a district were connected to
district headquarters by these optic fiber networks.
Date of birth: 03-08-1951.
Education: B Sc Maths and Physics.
Employment:
1974-
Telephone operator.
1980-
Telephone inspector.
1084-
Junior Engineer.
1999- Sub
Divisional Engineer.
Retired from service on 01-02-2009.
Some important changes:
- Mores
code telegraphy
- Manual
telephony
- Electro-magnetic
strowger exchanges
- Cross-bar switching systems
- Teleprinter
[telex] exchanges
- Electronic exchanges
Trunk lines:
- Open
wire trunks[physical line]
- Three-channel carrier systems
- Eight
channel systems
- Microwave
links [line of sight communication links]
- Digital
microwave systems
- Optic
fiber cables links[light wave guides]
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