Abstract: A concentration method and concentrator arrangement enable a plurality of synchronous or asynchronous data terminals to be served by a common B channel of an ISDN to which the data terminals are connected by a digital subscriber termination and terminal adapters for transmission in packet mode. The terminal adapters are connected to the digital subscriber termination at the S0 basic access level. In the event of a request for B channel communication between a first data terminal served by a first terminal adapter and a packet mode ISDN port to which a second data terminal already has access via a second terminal adapter and via a first B channel, a transit connection is established between the two terminal adapters via the digital subscriber termination using a second B channel. Data packets conveyed between the first data terminal and the ISDN port are conveyed via the terminal adapter of the second data terminal.

Abstract: Telephone subscriber connection system based on a ditital time-division switch. System of connecting telephone subscribers whose devices (2) are connected to junctors (6, 7) of a digital time-division switch (1) controlled by a central processor (5). Each junctor is identically connected to the switching network (4) of the switch by the same number of channels of a shared time-division multiplex link (LM0), all information concerning a junctor passing on these channels between the junctor and either another junctor or the central processor. The latter has direct access to the switching memory (17) of the switching network enabling it to read or write there directly. Requests addressed to the central processor (5) from the devices (2) connected to a junctor (6) are directly transmitted by this means to said central processor.

Abstract: Apparatus for checking electrical connections switched through an automatic switching machine. Idle circuits (P1, Pn) e.g. subscriber lines and outside lines, are connected in turn through the switching machine to the terminating set (Tr) thereof. Tone is applied via the normal tone-feed circuits (GT C1 to Cn, TL1 to TLn) to the idle line and the tone is detected at the terminating set. All lines at the terminating set are scanned (Y1 to Yn) in turn to check for any possible cross-connection and then the next idle circuit is tested. The apparatus forms an integral part of the switching machine.