Test jack frame, cabinet

Keybridge House was built in the 1970s to house both an international and an inland telex exchange. Keybridge was also designed as a trunk telephone exchange (an exchange that connects other exchanges) for London and the South East and as a telephone service centre where a large team of engineers was based. In 1984 Keybridge became a state-of-the-art international digital telephone exchange.

This test jack frame was manufactured by Plessey, at the time Britain's largest telecommunications manufacturer. The device was used to test telex lines to Asia. The cities can be seen on the blue magnetic strips. Significantly a number of these lines were used by news agencies with offices in London to send telex messages. The engineer would plug a lead into the corresponding socket and then a red light would come on if the line was functional. The names of the news agencies can be seen above the sockets.