Abstract: A circuit arrangement for telecommunication switching systems, including PCM time division multiplex telephone switching systems, with double central switching matrix by which two corresponding line trunk groups comprising a sub-switching matrix each and a group control unit each, are allocated to each other in pairs via two time-division-multiplex lines. The line units and the PCM-lines leading to the central switching matrix, which are individually respectively allocated to the two line trunk groups, and which are connected with the respective sub-switching matrix of their own line trunk group during normal service, are switchable, during emergency service of one of the two line trunk groups, to the sub-switching matrix of the respective other line trunk group.

Abstract: A telecommunication exchange system has a plurality of switch facilities over which signals are emitted on an average only during a part of their respective occupation. A signal current source for emission of the signals is provided having a call-handling capability limited by signal current load. A signalling system is provided for serving a distribution of the load and provides pulse sequences having respectively identical pulse spacings. Pulses of different pulse sequences simultaneously transmitted over different switch facilities have chronologically different phase relations and a chronological offset from switch facility to switch facility. The offset is such that the pulses of the different pulse sequences connect chronologically to one another with respect to pulse termination and pulse beginning. The switch facilities are allocated for receiving the pulse sequences from the signalling system to a respective one of the pulse sequences of a specific phase relation.