Abstract: A microcomputer integrates a Digital Subscriber Terminal (DST) adapted to an Integrated Services Digital Network (ISDN). In addition to the electronic circuit boards that ensure all the normal data processing and management functions (central processing unit, input/output circuits, ROM and RAM circuits), the microcomputer is equipped with an additional set of circuit boards for interfacing with an ISDN system, so as to constitute a microcomputer-contained DST for an ISDN. The management and switching of data concerning the ISDN system are provided by the additional set of circuits, so that the DST function is achieved without calling on the resources of the microcomputer's central processing unit. In this way, the essential telephone switching function is obtained without calling on the PC's central processing unit, while the integration of the DST within the PC makes it possible to benefit from the computer's data processing functions with a minimum amount of equipment for a maximum number of functions.

Abstract: A transmission configuration between a main station and a local station consists of a line which permits supplying of direct voltage power for stations from a source within the main station. A rectifier bridge is installed in such a manner that suitable polarization of the receiver can be achieved, regardless of the branching direction for wires comprising the line. Groups of unipolar current impulses are superimposed upon the supply voltage along the line by two generator units (K.sub.44, 40 and K.sub.50, 46) within the main station and a generator (K.sub.102, 100) within the local station. The respective polarities of impulses sent to and from the main station and the local station are such that said impulses can flow through rectifier bridges within local stations.

Abstract: A subscriber's telephone line equipment for connection to a telephone exchange for replacing a telephone transformer or other kind of transformer. The equipment comprises a circuit connected to the telephone line which comprises two voltage sources, a chopper circuit, a voltage-doubling rectifier, a current-limiting circuit and a closed-loop detecting circuit, and receiving and transmitting circuits connected to said telephone exchange.

Abstract: A network for a time-division multiplex-frame telephone exchange with pulse code modulation, the network being capable of connecting 2.sup.n+p+q subscriber's lines (n,p,q being integers) to a plurality of coders, comprises a plurality of first multiplexers respectively connected to the subscriber's lines, a plurality of demultiplexers, two pairs of second multiplexers connected to the plurality of demultiplexers by odd and even buses, and cyclic control means for controlling said first and second multiplexers, said demultiplexers, and said coders.

Abstract: A telephone junctor for interconnecting an electromechanical and an electronic automatic exchange, the latter using tone signaling and capable of operating in time-division-multiplex. The junctor permits direct inward dialing of a subscriber on the electromechanical exchange by a subscriber of the electronic exchange.

Abstract: An electronic replacement for a telephone transformer for connecting a two-wire circuit to a four-wire circuit comprises a first differential amplifier having a constant gain feedback loop. The feedback loop comprises an opto-electronic coupler and a second differential amplifier. A DC source connected to the first differential amplifier by a switch produces biasing current for a photo transistor in the opto-electronic coupler. A DC supply to the line on the two-wire side is provided by a source connected to the wires by transistor circuits connected as active reactances.

Abstract: A d.c. power supply circuit for a telephone line which utilizes transistor circuits having an active reactance to replace the telephone transformer. The transistor circuits each transform a capacitor into an effectively inductive reactance, thus resulting in a cost and space savings.

Abstract: Electronic time switching telephone system so that the operator can listen in, with the ability to break-in and talk to the correspondents connected to the corresponding exchange, the system comprises an interface modem between the operator's line transformer and the connection network.