The telecommunication system (e.g. a switching telephone exchange) provides a plurality of modular units each comprising a microprocessor, which result to be full-mesh connected with one another by way of communication channels (C). The circuital arrangement provides the presence of a transmitting section (ST) and a receiving section (SR) which are placed in each of the modular units (MO) of the system. The microprocessor (CPU) transfers the messages to be sent to the other modular units (MO) into the transmitting section (ST) associated therewith. The transmitting section is equipped with means adapted to apply a prefixed polarity to the communication channel (C) associated with the modular unit which the message received from the microprocessor (CPU) is destined to. The receiving section (SR) of each modular unit cyclically scans the channels associated therewith, stops the scanning at the communication channel on which it detects the presence of said polarity and at the same time provides for sending an activation signal for the transfer of the message on a signal channel (c) associated with that communication channel (C). The message is therefore emitted in response to the reception of said control, it is stored in the receiving section (SR) of the modular unit of destination and then transferred into the relative microprocessor (CPU) (figure 2).