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In an electronic telephone exchange designed for public service in the United Kingdom network, speech and other signals are transmitted as pulse amplitude modulated pulses over unidirectional highways carrying 8210-kc/s pulse channels. Line and interhighway switches are controlled by magnetostriction delay line stores; delay lines also store supervisory and register information and an inductive store is used for semipermanent line information. Connections are set up by triplicated common equipment using stored program control techniques. Comprehensive error checks are provided, together with alternative paths through the exchange.