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Events in telecommunications history

1933

Imperial Chemical Industries Ltd. discovered polyethylene, or polythene as it became known. This material, because of its low dielectric constant, became widely used for submarine cable insulation in place of gutta-percha and rubber, and for many other purposes in telecommunications.

Telephone service was opened with India, Northern and Southern Rhodesia and Turkey.

Phonogram work was transferred from telephone to telegraph staff.

'Demand' trunk service was extended to group centres.

The first nine-channel (bothway) voice frequency telegraph system (using a four-wire telephone circuit) was brought into service. This system provided automatic calling clearing and supervisory conditions over long-distance circuits.

The British Telephone Technical Development Committee (BTTDC) was set up to co-ordinate development work between the Post Office and the five manufacturers party to the Telephone Exchange Equipment Bulk Supply Agreement. These manufacturers - ATE, Associated Electrical Industries, Ericsson Telephones, GEC and STC - were represented on the Bulk Contracts Committee which allocated telephone exchange business on an equal share by value basis. Before the creation of the BTTDC each manufacturer had individually carried out their own design and development for Post Office contracts. As a result of the setting up of the BTTDC all development work for the Post Office was shared between the five parties and all information produced for the Post Office was to be known to all parties. The aim was to standardise equipment design and obviate parallel development. The Post Office and its five exchange equipment suppliers were now able to coordinate further development and promote a high degree of standardisation of circuitry and components, particularly of relays and selectors.

A separate exchange for international calls was opened at Faraday Building in Queen Victoria Street, London. It had 121 sleeve-control positions equipped for 480 circuits. Known as the 'switchboard of the world', cable and wireless telephone channels radiated from Faraday across the globe. The later use of high-frequency radio circuits, which involved rather different operating techniques, required the opening of a specialised exchange in Wood Street.

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