Abstract: A digital time switch system includes a switch core and a number of switch ports. The digital time switch system is intended for use in a telecommunication network, in which the switch ports share the bandwidth of a bus by time-division multiplexing. The bus is separated into time slots that are assembled into frames. Data transmission between the switch ports is performed in time slots that have been assigned to a respective switch port by a superior control unit so as to prevent bus conflict. Each switch port has access to the whole bandwidth of the bus and chooses through the superior control unit the data which is intended for the switch port. Logic in the switch ports is arranged to give a certain logical value to data directed to the switch core and appearing in unassigned time slots.