Abstract: A method of integrating one or more accessory function modules in telecommunication systems is disclosed, especially digital telephone extension systems, where communication between two user terminals is achieved using time division multiplexing by assigning a pair of time slots through a central exchange, and by preassigning at least one particular time slot which can be accessed to allow communication between the accesory function module or modules and the user terminals.

Abstract: An improved switching apparatus, having group couplers (30) and a loop arrangement (6) including a plurality of single loop lines, for communication of digital signals, particularly PCM signals, each comprising several bits at a fixed transmission rate to or from connection circuits (35, 36) connected to a plurality of group buses (31, 32) on each of which digital signals can be transmitted in parallel in a predetermined number of time compartments in cyclic repetition in pulse frames. The group buses (31, 32) are connectable by way of a respective one of the group couplers (30) to the line segments (25, 26) of a respective main bus associated with one of the main couplers (13, 14) connected to segments (7, 87) of the central loop arrangement (6). The two line segments (25, 26) of each main bus serve to transmit digital signals in different directions.

Abstract: The invention comprises a circuit arrangement for the control of digital signal transmission, particularly PCM-signals, between stations of a time division multiplex telecommunication system, particularly a PCM-time division multiplex telecommunication system, with a central control unit, via a multiplex channel to which every station can be connected and on which every station included in a connection is allocated a transmission pulse with cyclically repeated time slots occurring in successive pulse frames and a reception pulse with cyclically repeated time slots occurring in successive pulse frames, with stations combined in a group of stations jointly connected to a transmission trunk by their transmission outputs and to a reception trunk by their reception inputs, and with all trunks connected to the multiplex line via amplifiers. In this context digital signals are understood to be voice signals and data.