Abstract: System for processing signalling relating to user equipments for the core system of a telecommunication installation constructed around circuit mode units connecting user equipments, auxiliary units and/or control or processing equipments. Each unit has means for adapting the signalling information for said user equipments, auxiliary units or control or processing equipments connected for transmission of said signalling information internally in a standardized form which can be switched by the unit and means for preprocessing signalling information to the benefit of the microprocessor, the auxiliary unit or the control or processing equipment responsible for processing it.

Abstract: In a method of synchronizing nodes of a private telecommunication network to the best available clock at all times, each node of the network is normally synchronized by externally originated clock signals which reach it via a point-to-point digital transmission link input. Two node inputs are preselected as main and backup master clock inputs and each node is selectively preselected as a potential supplier of clock signals to each of the nodes to which it is connected by one of its master clock inputs, the nodes of the private network interconnected in this way determining a synchronization tree. In the event of loss of clock signals an exchange of information is instigated between adjacent nodes to reconfigure the synchronization tree that these nodes constitute so that each of them is synchronized to the best available clock.

Abstract: In a data transmission method employing a synchronous frame combining asynchronous cells with isochronous channels, a first channel of each frame is reserved for control data independent of the data to be transmitted. Second channels of each frame in a multiframe are reserved for path service data divided between a first group of a specific number of the second channels having specific channel numbers reserved for asynchronous data cell service octets and a second group of second channels which specify the number of isochronous data channels used during the frame of which each forms part. The third channel of each successive frame is at least partially reserved for a code defining a cell start channel number for any cell in the frame in question.