Gisborne TMX – Part 2

Gisborne telephone subscribers dialling “0” in the late 1970s were often struck by how bright and crisp the ringing tone sounded when compared with the sound heard when calling friends or neighbours.

At the time, Gisborne’s central exchange used 2000-type strowger switching equipment, better known as “step-by-step” switching. As they had only dialled one digit to call the operator, there was only one switching stage involved in connecting the call, instead of the usual three (for a four digit number) or four (for a five digit number) meaning that the ringing tone was louder.

On the Gisborne toll board, the incoming call would have lit a lamp on a strip labelled GS (for subscribers on the Gisborne city exchange), WOI (for subscribers on the Waerenga-o-kuri exchange), NGB (for subscribers on the Ngatapa exchange) etc. while the caller received ringing tone.

The board in front of the operator was built up of alternating rows of lamps and jacks arranged in 19 inch rack mounts, allowing each lamp to have an associated jack below it for receiving the operator’s cord. In general, trunks were arranged in groups of ten, repeated at regular points along the length of the toll board allowing each operator to access any call within three 19 inch verticals – not too long a reach. This practice worked well for smaller toll boards like Gisborne (which from memory was 20-odd positions), but on the massive sprawling boards in larger cities like Auckland, Wellington and Christchurch, the boards had to be broken into sections which had to be permanently staffed to allow all calls to be answered.

To answer the call, the operator simply plugged a cord into the jack below the glowing lamp, threw the key switch associated with the cord pair to “talk” and uttered the familiar “Tolls here” as they reached for a toll ticket to record the details of the call.

The caller would be required to give the required telephone number, their own telephone number and additional information such as names if a “person-to-person” call was required. Honesty was a key component of the times, as there was no such thing as “Calling Line ID” (CLI) to identify the caller, and the system generally worked well. Persistent fraudsters usually became known, and operators were generally alerted to scams during briefings as they signed on for their shifts.

During the 1960s and early 1970s, Gisborne was connected with the rest of New Zealand via a 48 channel VHF (Very High Frequency) radio system from the VHF Station on Kaiti Hill. This limited number of trunks was insufficient to meet demand at peak times, and it was not unusual to be told “There’s a short delay, we’ll call you back in 10 minutes” after giving the operator the details of the call.

However, by the middle of the decade, Gisborne had been added to the national broadband network, and the toll board had direct trunks to Napier, Wellington, Auckland, Auckland International and other destinations.

These destination circuits were also arranged in groupings, repeated on multiples along the length of the toll board. However, as the entire system operated on 50 volts DC, a different signalling system was used to prevent glowing lamps from overheating the installation and reduce the need to replace blown bulbs. Incidentally, this consideration was not mere puffery, as I recall being told that toll boards at Auckland and Wellington had suffered heat damage from glowing lamps in an earlier “go-slow” by staff when I joined midway through the 1970s.

Free Line Signalling (FLS) was used to illuminate a lamp above the next available circuit to, say, Wellington and, as the operator selected that trunk circuit, the indicator lamp would be extinguished and a lamp would start glowing above the next free circuit.

Having obtained the details of the call, the operator would plug the other cord of the pair into a free circuit to the desired destination, dial an access code (if one was required to reach one of the outlying exchanges) and the required telephone number. The operator would stay across the circuit until the call was answered and announce “Gisborne calling. Go ahead, please” although by the latter part of the decade this had been shortened to “Go ahead, please.” As the operator withdrew from the call, a toggle switch on the meter associated with the pair of cords was thrown, and the mechanical meter would begin counting meter pulses.

At busy times, the sound of the call meters operating was very noticeable, with a distinct “click CLACK” as the electromagnets operated and then released with the spring mechanism pulling the meter cams around one notch.

If a call was made to a subscriber on a manual exchange, the operator would call a counterpart at the manual exchange such as Ruatoria and announce “51M for Gisborne, please.” The Ruatoria operator would use another pair of cords to connect the call from the Gisborne operator to the party line for subscriber 51, use an attached switch to ring out the morse code equivalent of the letter M and, if the call was answered, the Gisborne toll operator would announce the call and the conversation could proceed.

From memory, the toll meters were two-unit meters, so when the meter reached its maximum count of 99 on a lengthy call, an associated lamp would start flashing. This would require the operator to call a supervisor who would walk over to verify that the conversation was still in progress, the meter reset plunger was then pressed, and the meter would start counting from 01 again.

Not surprisingly, with all this manual intervention, toll call rates were higher in those days.

One Response to “Gisborne TMX – Part 2”

  1. Flying deldas says:

    Why did your joining cause a “go-slow” by staff which resulted in heat damage of the glow lamps?
    Signed: Chief nit picker

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