In the mid-Sixties, style, innovation and
design were all important. The Trimphone met all of these
criteria: It was a modern, stylish phone and the first to
have the handset placed in line with the dial, instead of at
right angles.
GPO Leaflet PH1089 -
Design John Ward, Photography Alan Marshall.
Tone - The first BPO
(British Post Office) telephone to have a Tone Caller in place of a
bell.
Ringing -
Adjustable volume settings for the tone caller... off, soft, <,
loud.
Illuminated - A
radio-active dial!
Model - A
stylish case in a choice of 3 modern colours... Two-tone Blue,
Grey/Green, Grey/White.
A compromise between style and function, the
Trimphone has remained the topic of conversation (literally) for well
over 30 years*, since its first appearance in 1964. [* at the time of writing]
Critics disliked its tendency to slide about as you dialled a number.
Others were caught out by its acoustically coupled microphone. There
were reliability problems with early versions. And the heavy-handed
discovered that the handset rest could easily be broken. Overall though,
the Trimphone was a status symbol, stylish, sexy, sleek, and a big
innovation in terms of design and appeal to the disconcerting telephone
user. It boasted many special features, bringing together the best of
the evolving telephone technology. The Trimphone remains a
design icon of the 20th century and these pages serve as a reminder of
its many incarnations...
In the early Sixties, a new type of dial telephone was
developed for the Post Office under the British Telephone
Technical Development Committee.
By 1964 the Standard Telephones and Cables produced
Deltaphone was introduced.
In 1965, the Post Office named this product the
Trimphone and an initial quantity of 1000 phones were
released on trial into the rental market.
The Trimphone was given the engineering code of Tele
No.712.
By 1971 the new version, Tele No.722 had an improved
transmission board, comparable to the standard 746 dial
telephone.
STC's press-button (SC) Deltaphone was launched in 1973
(approx) and trialled as the Post Office's Tele No. 1/766
during 1974.
Tele No.786 the MF Trimphone followed in 1979 (approx).
In 1980, British Telecom's Special Range Telephones
included, the Deltaphone & Deltaphone Deluxe.
Finally in
1982-The Phoenixphones which were refurbished, repackaged Trimphones.
In the early Sixties, a new type of dial telephone was
developed for the Post Office under the British Telephone
Technical Development Committee.
"The Trimphone had a neat, stylish, lightweight handset,
easy to hold and untiring on the arm for those long chats on
the phone. The Trimphone was a fashion statement, not
something to be hidden away. To facilitate comfortable
telephoning, the Trimphone had a long stretchy (helical)
matching colour line cord."
Here we take a look at the evolution of the GPO branded
Trimphone in all its versions from the dial through to
modern press-button...
With some exceptions, contracts for the supply of telephones
to the British Post Office (BPO), were placed with leading
manufacturers whom also sold the products in their own
right, often exporting abroad. Thus the Deltaphone as made
by STC was named the Trimphone when marketed by the BPO.
The Trimphone's luminous dial, was produced by a
radioactive Betalight...
The dial of the Trimphone is illuminated by means of a
c-shaped sealed glass self luminescent tube coated
internally with phosphor and filled with tritium gas.
"The low-energy Beta radiation energizes the
fluorescent coating and is then absorbed by the glass. The
secondary radiation (Bremsstrahlung) which then arises has
been confirmed by both the Post Office Radiological Officer
and the Radiological Protection Service to be much less than
the recommended maximum for luminous wrist watches. The tube
is expected to have a useful life of at least 10 years."
[Post Office Electrical Engineers' Journal, Vol 58 Part 1 April 1965]
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