More Info on the 700 range

The Telephone 706 was designed jointly by Ericsson's Telephones Ltd, The GPO Engineering Department and the Council of Industrial Design.  It featured new ideas already used in several telephones introduced during the previous decade.  The handset was previously used on the prototype Telephone No. 700, which was field trailed but never released as it was superseded by the plastic cased 700 range.  The handset which was hollow and made of a heavy plastic then became a plastic moulded handset.

Unlike the 200 and 300 types the 706 was at last a truly modern looking telephone. It had smooth curves and ergonomic design, was lightweight, colourful, and versatile.  The same telephone could be used for many applications by changing the removable dial surround and also had a blanking plate covering a hole which could be removed to allow different switches to be fitted.  Inside it contained the latest circuit technology including a plug-in current regulator and option of printed circuit board wiring.

Three telephones which possibly influenced the final design of the telephone 706 are:-

1) (1953) Ericsson's/GEC '1000' type - smooth curves and various colours...

2) (1957) Siemens 'Centenary Neophone' - lightweight plastic, removable dial surround, various colours, the first UK telephone with printed circuit wiring.

3) (1949) #500 Rotary Desk Set - designed for Bell Telephone Co in USA by Henry Dreyfuss (This is the 'standard' American desk telephone).

A quote from Henry Dreyfuss regarding the #500 Telephone goes 'The form had to be classic so that it would not be out of place with shorter lived objects in homes and offices - he estimated that it would have a twenty year life span. This telephone is known-to anyone who has read a magazine or watched a television programme during the last 30 years and must surely have influenced the design of many of its predecessors.

The Telephone 706 was available in 7 colours ... Two-tone Green, Two-tone Grey, Topaz Yellow, Concorde Blue, Lacquer Red, Black, Ivory.  Other variations exist:- Single-tone Green, Red & Ivory, Orange and transparent.  The clear plastic version was also used for demonstration purposes.  The Council of Industrial Design originally suggested 'Colonial Blue' for the blue version but Ericsson's asked for it to be changed because "it was inappropriate in a changing world".  The two tone grey version reflected "trends in matching office equipment".

The case and handset were made of lightweight thermoplastic acrylic.  The trade name of this was 'Diakon' and was manufactured by ICI.  Internally the '706' contained improved (over the 300 type) circuitry including a plug-in electronic regulator.

Two designs were submitted for the internal wiring of the Tele 706... Conventional wiring and printed wiring.  In 1959 printed wiring techniques were in their infancy and thus the BPO allowed manufacturers to choose either method of production.  The two methods had the same terminal layout and used the same components.  Siemens Edison Swan Ltd designed the printed wiring version, whereas Ericsson's Telephones Ltd preferred the conventional method (Siemens had already produced the first telephone with printed wiring inside - the Centenary Neophone).

Instruments with conventional wiring have a plastic base with raised domes for the bell gong mountings, whereas printed wiring instruments have a pressed steel base which is flat.

The following manufacturers were involved in the production of the 706 initially:-

The Automatic Telephone & Electric Co, Ericsson's Telephones Ltd, The General Electric Co Ltd, The Phoenix Telephone & Electric Works Ltd, The Plessey Co Ltd, Siemens Edison Swan Ltd/ AEI, Standard Telephones & Cables Ltd and The Telephone Manufacturing Co Ltd.

BPO instruments have also been seen with HAS (Association Automation, London) & CWL (Pye Cambridge works) manufacturers codes.

GEC called the 706 'The New Gecophone' whilst Ericsson's called it 'The Etelphone' - it was also known as 'The Mod T' by Post Office sales staff (Modern Telephone).  This telephone was given the title '800' type by AEI.  A version with a 2000 Ohm ringer and North American number ring was made for the Canadian market.

On earlier models the resistance lamp on the regulator board had just a clear glass finish - unfortunately some users were perturbed by the glowing coming from within their instruments if they were used in the dark (especially red models!) and later releases have the resistance lamp painted black.

Telephone 746
In 1967 the 746 Type telephone was introduced.  This was an improved version of the 706 range and offered similar facilities.  The case styling is different from the 706 although it retains the same overall look.  Inside the circuitry is different in that the regulator components are soldered directly onto the printed circuit board.  No conventional wiring version was produced.  The same colour options as for the 706 were offered to the customer.

The Tele 746 was later produced with the new style plug type lead (renumbered as the Tele 8746) and marketed as the 'Yeoman' which was also available in Brown.

The First Luxury Telephone...
Prior to 1965 customers in the UK telephone network were not given any choice of telephone instrument.  During the early 1960's the Post Office was revising its commercial outlook and decided that it needed a luxury telephone to add to its range and in 1961 the Post Office informed industry that this was the case...

Several firms were developing telephones for export, out of their own resources, that might have met the Post Office's requirements and various models were submitted for test during 1962.  Two years of testing and market research then followed.  Towards the end of 1963, one manufacturer, STC, decided to start tooling up for export and all the other firms withdrew.

The Trimphone
The outcome of these endeavours was the Telephone No 712 or Trimphone.  The (then) modern design incorporated the novel feature of dial illumination, tone calling and a unique handset.  The initial four letters of the name Trimphone stand for Tone Ringer Illuminated Model.  The Trimphone was designed by Martyn Rowlands.

The handset was coded 'Handset No. 8' and featured smaller transducers (Inset Receiver No 13 and Transmitter No 15) mounted adjacent to one another in the earpiece cavity.  The transmitter being coupled to the mouthpiece by an acoustic horn.  The transmission circuitry was based on that of the telephone No 706.  The Trimphone was the first in the BPO range to use a tone caller which warbled at around 2000Hz modulated by ringing current.  The volume of the ringer gradually built up over the first few cycles of ringing current.  There is a volume control in the base of the telephone with LOUD, MEDIUM and SOFT settings.  Some people were able to mimic the sound of the tone ringer by simultaneously whistling and wobbling their lips... a vulgar habit which should be frowned upon.

Production of the new telephone commenced in 1965, and an initial quantity of 1,000 was offered to customers on a selective trial basis.  It then became freely available, at extra rental cost, with a choice of three two-tone colour schemes: Grey-white, Grey-Green and two-tone blue.  The hollow handset led to some embarrassing results when customers attempted to cover the mouthpiece by hand in order to make a confidential aside - the sound was still transmitted inside the handset!
Another problem with the dial version of the Trimphone was its light weight, 0.8kg compared with 1.4kg for the 700-type and 2.6kg for the 300-type telephone.  This led to the complaint that on slippery surfaces the telephone turned and slid whilst dialling.

There was also some concern about the luminescent dial which glowed green in the dark.  Although the radioactivity was equivalent only to that given off by a wristwatch it was felt wise to withdraw this facility as public concern over radioactivity grew.  An improved version, the Telephone No. 722, was introduced in 1971.  This had the same outward appearance as the original, telephone No. 712, but had the improved transmission circuitry of the telephone No 746.

The First Keypad Trimphones
The first keypad version of the Trimphone appeared in 1977 - somewhat delayed by the problem of packaging the signalling electronics into the small volume of the Trimphone.  The problem was alleviated by marginally increasing the height of the case compared to the dial version.  The first design of keypad Trimphone to achieve large-scale production was the SC version (Tele 766); this design incorporates relays, but no batteries are needed. Subsequent designs have eased the packaging problems further by eliminating the relays and introducing transistor pulsing.  An MF4 (Touch-tone) design had to await the development of an integrated circuit to replace the bulky coils and capacitors otherwise needed.  This was introduced in 1979 (Tele 786).

The Deltaphone
The next incarnation of the Trimphone was the Deltaphone.  This should really be in section 5 but the notes have been included here to for continuity.  By 1980 Trimphones had been around for some 15 years and needed revamping for the new era of competition.  STC gave Trimphones this new lease of life by renaming the dial version as the 'Deltaphone' and the MF version as the 'Deltaphone Deluxe'.  The transformation was tastefully completed by cladding these unfortunate instruments in leather.  Mid-brown for the Deltaphone and a choice of Red or Green for the Deluxe model.

The Phoenixphone
The final incarnation (or rather reincarnation) of the Trimphone was a collection of alternative colour range Trimphones. These were the first part of a series of telephones known as 'Phoenixphones' and this first set was called the 'Snowdon Collection' and appeared around 1982.  Six two-tone colour combinations were chosen 'by leading design consultants' and were available in both dial and press-button versions.  It is believed that Lord Snowdon had a part in these colour choices...

Olive Green   Beige
Dark Orange   Orange
Dark Red   Red
Black   Grey
Light Green   Mid Green
Brown   Cream

The telephones were refurbished (or rose from the ashes! hence the Phoenix association?) and were fitted with the then new PSTN cords.  No rental option was available only outright sale at 35 for the dial version and 46 for the Press-button model (both prices include VAT.  The sales literature pictured a press-button Phoenixphone languishing on a rush table mat with a scallop shell (ash tray?), flip-up photo album and dried plant.  Was this taken in Lord Snowdon's front hallway?

The Trimphone - conclusion.....
The Trimphone has been with us in one form or another for some thirty years now, and although it is unusual to see one in use these days there are still quite a few around... in fact Trimphones are still seen for sale either new or refurbished in some telephone shops at the time of writing! (1995).
Despite the complaints in the early days about it slipping whilst dialling the Trimphone has become one of the icons of British telephone design and has surely earned the right to be in any discerning telephone collection!

Most of the Trimphone notes were gratefully obtained from IBTEJ V5 p263, IPOEEJ V58 p8, IPOEEJ V74 p239 & BPO sales literature.

The Compact Telephone
Jubilee/Compact Telephone - Tele 776 was first introduced in 1977 a limited edition in the colour 'Balmoral Blue' to mark the occasion of the Queens Silver Jubilee.  It was later made available in a choice of two colours (Stone or Brown). It was the first telephone aimed at the residential market.  Its compact fore and aft dimensions allowed it to be sited on a narrow ledge such as a window sill.  It required a separate Bellset which could also be mounted on a wall to form a shelf for the Compact Tele.  It employed the standard Tele 746 circuitry with a new ringer unit, the Uni-coil Bell No. 79.  This ringer then became a component option for the Tele 746.

The Phoenixphone
As mentioned previously in the notes for the Trimphone there was a series of telephones known as Phoenixphones which were available only for an outright sale from telephone shops.  The first Phoenixphones were Trimphones (Tele 8722G's) already described which became available around 1982.  I have also been told of two other issues - the second in the series were Tele 8756's (SC versions of the Tele 746) which were available in the following colours Pampas/Primrose/Lime/Mushroom/White.
A final third 'Phoenixphone' was the Tele 8706F available in Grey or Ivory.

Misc Notes :-
Removal of cases undo the two screws near to the switch hooks on 706 types or above the cord entry holes at the back of 746 types.  Then pull the cover up from the base at the back of the instrument.  It is sometimes necessary to pull the dial towards the front of an instrument by inserting a finger in the digit '0' hole.  If problems are encountered do not exert unnecessary strain on the instrument... first check that the screws are fully loosened... if so then it is probably the case catching the dial fingerplate.  The best way to avoid damaging the instrument is to simply remove the dial fingerplate (see next item).

Removal of dial finger plates :-
The dial label cover glass needs removing first.  The correct method is to use an 'Extractor No. 29' (which is basically a rubber sucker!) or on early coloured plastic dial finger plates, a screwdriver No. 2 (small flat bladed screwdriver).  I would advise that anyone wishing to remove these covers obtains some sort of rubber sucker for their tool kit - it will prevent cracks and chips which will almost certainly arise if other methods are attempted... however the use of Sellotape is an alternative if no rubber sucker is available (other methods exist, but can often cause damage to the cover glass - find yourself a rubber sucker - it's not worth the risk!).  Once removed the dial label can be lifted and removed revealing a screw head in the centre of the dial.  Unscrew this and the fingerplate can then be lifted off.

Type Codes:-
Some instruments are marked (for example) 706F, 746F, 706L, 746L, 706R, 746R etc..  The suffix letters F, L & R have the following meanings:- F - All Figure dial or Dial Surround L - Figures & Letters on dial Surround R - Recall button fitted.  Other suffix letters exist.  I hope to add them later!
87xx Series Telephones and some telephones in the 7xx series were issued as low impedance versions with a PSTN type lead.  The type number for these instruments was the same as the original instrument prefixed by an '8'.  Thus a Tele 8746 is a modern version of the Tele 746.

Line Cord Connections Line cord connections to a standard Tele 706/746 are as follows:- Red - T8 , White - T1 8, Blue - T5 , Green - T4 straps T5-T6 , T8-T9 , T16-T17-Tl8-Tl9
Note: This is for the original 4 way lead - see section V for plug type lead.


Further Reading :-
Tele 706 - IPOEEJ Vol 52 page 1 Tele 712 - IPOEEJ Vol 58 page 8
Tele 776 - IPOEEJ Vol 68
Standardisation and Control of Colour for the 700 Type Telephone' IPOEEJ Vol 56 p247
'Customer Apparatus' (1956-1981) - IPOEEJ Vol 74


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Last revised: June 06, 2013