Digital telephone system

Claim 1

Apparatus in digital telephone systems including a switch-less central exchange (EX) of the time multiplex type, with a plurality of time channels, the exchange including first line circuits (DEC) for connection via lines to second line circuits (DIC) arranged in telephone sets (TA), said second line circuits each including means for coding and decoding pulse code modulated signal words, said exchange and lines being arranged for transmission of digital information in time-division form between said telephone sets and the central exchange including a central processor (EXCP) common to the system, a plurality of speech control boards (CCDX) and a plurality of line boards (LIDI), each of the boards including a separate regional processor (RP), said exchange, for establishing speech channels and transferring information between said telephone sets, including: in each line board (LIDI), at least one line circuit (DEC) having a plurality of inputs and outputs and including channel selection means (CHR) which, under control of the central processor (CP), connect, via said regional processor (RP), said line to an optional channel determined by the central processor, at least one first input and at least one first output of the line circuit (DEC) being connected to a communication bus (TB) common to at least some of said line circuit units (DEC), at least pulse code modulated signal words being exchanged via said bus, and at least one second input and a second output of a plurality of said line circuits included in said line boards being connected to common inputs and outputs of said regional processor (RP), at least one input and one output of said regional processor being connected to a control bus (SB) common to all of said regional processor (RP) and controllable from said central processor (CP), through which bus control information is exchanged, and said speech control boards (CCDX) including a plurality of speech control units (SC) having inputs and outputs connected to said communication bus (TB) and further inputs and outputs connected to a common regional processor (RP) arranged on each speech control board, which regional processor is in turn connected to said control bus (SB) via inputs and outputs.