GPO telephones

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The United Kingdom General Post Office (GPO) had a number of telephones that were provided by them for connection to their exchanges. Until 1982 the GPO had a monopoly on the provision of all telephones within the UK and so the range was limited. Customers (known within the GPO as "subs", being short for 'subscribers') did not buy their telephones, they were rented from the GPO, together with the house wiring and the wiring connecting the house to the local network at a connection point known as a DP (Distribution Point). The majority of DPs were (and still are) at the top of what are still known in the UK as telegraph poles.

1 Candlestick
2 232 Type
3 332 Type
4 Bell Set 26
5 706 Type
6 710 & 713 Type
7 711 Wall Mounted
8 746 Type
9 756 Type Push Button
10 782 Type Push Button
11 Statesman
12 Tribune
13 Relate
14 Prelude
15 Trimphone
16 External links

[edit] Candlestick

The candlestick is much sought after these days. This one is a Type 150 circa 1929.

Candlestick

[edit] 232 Type

A Bakelite type introduced in 1934 and which remained in production until 1957.

232 Telephone attached on top of a bell set 26

[edit] 332 Type

A Bakelite type introduced in 1937. This was the standard telephone issued by the GPO from 1937 until 1959 and it came complete with a bell unlike the 232. It continued in production until the mid 1960's. This was usually only available in black although ivory, red and the especially rare green were produced.

332 Telephone

[edit] Bell Set 26

This was a bell set that was used either stand alone or attached to the base of a 232 type telephone to provide a complete telephone as a 232 telephone did not itself have a bell set.

[edit] 706 Type

This was a revelation when it was first released in 1959. It was a robust design and is still used today. It was available in two-tone green, two-tone grey, topaz yellow, concorde blue, lacquer red, black and ivory.

706 Two Tone Green Telephone manufactured February 1963. This sample unfortunately has a cracked dial, but is an early version as later dials were clear

706 Telephone inside showing the reversible regulator mounted vertically and shown in circuit

A feature of the 706 was a regulator that could be used or not. The idea was if the subscriber was close to the exchange, the regulator would reduce the sensitivity as it had been found that this telephone was too sensitive close to the exchange. The purpose of the regulator was to vary the amount of ac speech current flowing through the microphone and receiver, to prevent it being considered too loud by subscribers on short lines. The regulator consisted of a network of rectifiers, diodes, resistors and two thermistors.

The regulator could be removed for customers not close to the exchange by inserting the shorting part of the regulator and this was achieved by turning it upside down.

The regulator being used was the default and in practice the unit was normally left in circuit. Compare this with the inside of a 746 where the regulator is permanently built in.

706 Regulator unit, the red part being a string of diodes and the glass part are the thermistors. Note the thermistor is painted black so stop the glow being shown

706 Regulator reverse

[edit] 710 & 713 Type

This was the same as a 706 but had four possible buttons or lamps fitted at the top of the case. Dummy buttons were used where neither button or lamp was used.

[edit] 711 Wall Mounted

This was a 706 but of a design that could be wall mounted.

[edit] 746 Type

This was an updated version of the 700 type. It was introduced in 1967 and looked very similar, although it had a slightly different case design. In fact the only way to tell that it was a 746 was to look at the stamping on the base. Unlike the 706 type it had a built-in regulator that could not be removed. When modified for the current plug and socket system an 8 was added to the numbers, hence a 746 became an 8746. Strangely a brown case colour was added to the range.

746 Red Telephone, an early version with coloured dial

746 Ivory Telephone manufactured in February 1984 and still in use today, having been converted to use the current plug and socket

746 Brown Telephone an unusual colour which was added to the range when used on the current socket system, and at reasonable price

746 Inside showing built-in regulator, which can be identified by the long green part, which is a string of diodes, beside which are the thermistors

With modern exchanges the regulator is not required, but, although it can be removed from the 706, as shown above with the 746 the regulator is permanently wired in-circuit and cannot be removed.

The 700 series was able to have an additional button fitted, which was used for a number of purposes, for example Shared Service. The one shown in the picture was used to turn the bell on and off. If there was no button the blank was left in place.

A very well used 746, manufactured in January 1971, that spent its working life at a scrap merchants, with a button that turns the bell on and off

746 inside showing the mounting of the on-off button

[edit] 756 Type Push Button

This was a 746 type but fitted with push buttons instead of a dial. The push button just created the same signalling pulses as a dial telephone, which caused horrendous post dialling delay.

The model shown in the photograph is actually an 8756, which has been modified enabling it to be used with the current plug and socket system.

8756 Two Tone Grey Telephone

8756 Base, showing that this telephone was refurbished in August 1982 and the need to show that this was a telephone rented from BT

[edit] 782 Type Push Button

This was a 746 type telephone which could handle MF4(DTMF) signalling ( a British version of the American touch-tone signalling) which produced tones. Obviously these telephones could only operate to exchanges that could deal with MF4 but they were used on PABX systems that used MF4 for internal calls from the 1970s. This type of telephone solved the problem of post dialling delay on external calls, provided that the line was connected to an exchange which could handle MF4 signals. The TXE1 exchange could handle MF4 calls as early as the late 1960s. This was however a unique prototype exchange, which served customers in Leighton Buzzard : otherwise customers did not have access to MF4-capable exchanges until later models of the TXE4 system came into service in the late 1980s.

[edit] Statesman

This telephone was a loop disconnect when introduced in the early 1980s but was later available in an MF4 version. It was among the first range of BT phones to be available for outright sale in 1982. A novel feature of this phone was that both the dialling circuit and the transmission circuit were on a single microchip. The one shown in the photograph is a 9003R manufactured in January 1984 and is loop disconnect.

GPO Statesman 1984 Ivory

GPO Statesman 1984 Ivory Inside. Notice the lack of components as compared with the 700 series. It's all in the chip.

[edit] Tribune

This telephone was able to operate on both loop disconnect and MF4. The method was chosen by a switch on the base of the telephone which is shown in the photograph. It was introduced in the 1980s as a basic telephone and some models even had a mechanical bell.

GPO Tribune Blue

GPO Tribune Blue base. Note switch on the left hand side to change from Loop Disconnect to MF4. Also shows the wheel which is a crude method of adjusting the ringing volume

[edit] Relate

This telephone was able to operate on both loop-disconnect and MF4 and a switch on the base of the telephone chose the method. The volume of the ringer could also be change to High, Low or Off. Note the tray to the right, presumably to hold a pen or pencil. Note also that on the underside there is a mount that can be fitted in two positions. One makes it a desk telephone and mounting it the other way round turns it into a wall telephone - very ingenious.