Fast signalling in the UK telephone network

Recent developments in the UK telephone system have jointly resulted in a requirement for faster signalling between telephone exchanges. In a network using `Channel-associated¿ signalling, `line¿ signalling is usually effected on a link-by-link basis, and it is important to ensure that supervisory signals are repeated as quickly as possible. Fast `interregister¿ signalling commonly takes the form of multifrequency (m.f.) pulsing, using a `two out of six¿ code. In a wholly integrated digital network, direct coding of the channel bits to provide fast interregister signalling could offer an attractive alternative arrangement. A different signalling principle, applicable to both analogue and digital networks, uses separate data channels to convey both line and interregister signals. The method of signalling is more compatible with processor-controlled switching systems than other types of switching system, but may present cost problems on the smaller sized routes. The economic application of new fast-signalling techniques to register-controlled exchanges in a network composed predominantly of step-by-step exchanges presents serious interworking problems which may possibly be minimised by the provision of an `overlay¿ network. Because of the time required to establish the economic implications of such a solution, it may well be desirable at the present time to proceed independently with the introduction of m.f. signalling between registor-controlled exchanges over the existing junction network, using a system which is compatible with that already developed for the trunk network.