Abstract: An arrangement for connecting a personal computer (1) to a telephone network (2) via a digital exchange, in particular a private exchange (13), and via a telephone set (3) or subscriber terminal suitable for processing telephone signalling and enabling digital voice and data signals to be transferred simultaneously, the telephone set or subscriber terminal being controlled by an internal processor (14) of a controlling logic circuit (9) and including a data transmission (4B) for connection to a computer apparatus such as a computer. The coupler (4) is integrated in the telephone set and is connected to the controlling logic circuit (9) of the telephone set, which diverts the telephone signalling transmitted to the controlling logic circuit of the telephone towards an external access (1A1 or 1A2) to the bus of the personal computer, and which selectively replaces the telephone signalling which the telephone would normally transmit to the exchange by corresponding signalling produced by the personal computer.

Abstract: A synchronizing system for a private digital exchange (1) comprising a logic control unit (4) and specialized interfaces (9, 8) whereby the exchange is connected firstly to a plurality of subscriber terminals (2) via SO accesses, and secondly to a telecommunications network (3) via TO base accesses. The exchange includes a time base (6) which associates a fixed frequency local oscillator (7) with a phase locked loop (32). The system includes clock switching means suitable for imposing the first clock signals to come from the network (3) via an active one of the TO base accesses and the associated interface (8) on the phase locked loop (32) of the time base (6) as soon as said first clock signals come close in phase to the substitute clock signals provided by the time base (6) in the absence of said first signals from the network.

Abstract: The safety interlock for a cover of a housing in a telephone apparatus provides electrical safety for the user by requiring the apparatus to be disconnected from a telephone line before the cover of the housing can be opened. The apparatus is connected to the telephone line by means of a two-part pluggable connector, with one of the parts being a receptacle fixed in the case of the apparatus. The safety interlock comprises a flap (8) which slides inside the case (1, 2) of the apparatus over the opening (5) giving access to the telephone line connector receptacle, with the flap sliding between a closed position in which it disengages the opening (5) while holding the cover (8) of the housing closed, and an open position in which it obstructs the opening (5) while allowing the cover (3) of the housing to be opened.

Abstract: The mechanical safety assembly for a telephone set having a housing with a cover including a sliding lock for closing the cover (7). The lock includes an operating head (13) external to the body (1) of the telephone set or terminal. The head fits flush with the wall of the body (1) when in the closed position and leaving only smooth surface visible, one of said surfaces (23) being pierced with a hooking aperture (24) which is accessible by a tip (25) of a paperclip or ballpoint pen.

Abstract: A method of routing calls for a network of digital time-switched exchanges (A, B, C, D, E, F, D) interconnected by groups (18 to 28) of PCM time multiplex trunks, with each group ingterconnecting two exchanges. Each exchange establishes a utilization cost for each of the groups connected thereto. This cost is based on the busy fraction of the least busy trunk in the group of trunks under consideration and it is transmitted to all of the exchanges in the network in order to enable them to determine least cost paths for the calls that they are requested to set up.

Abstract: The protection device in accordance with the invention is connected in series with the line. It comprises either a circuit (1) for providing protection against voltage surges, or else a filter (2) for providing protection against radio frequencies, or else both said circuit and said filter. It protects terminal equipment (telephone set, data terminal, fascimile machine, etc.) against disturbances both in differential mode and in common mode. The device is mounted in a protection connector which may either be of the wall socket type or else of the removable adapter type for plugging into a conventional wall socket, and in either case the terminal equipment has a plug which plugs into a corresponding socket of the protection connector.