Abstract: A switching exchange of the space switching type is adapted to provide interconnection of the lines of a communication network, each line being able to provide several multiplex channels, each channel being different from the other ones in the frequency domain, in the time domain or in any other way. The control unit of a switching exchange of the space switching type is adapted to enable the system to interconnect more than two lines of the multiplex type together, by the provision of complementary logic which determines for any new connection of multiplex lines whether the required connection is possible or not in accordance with the state of the network when this request occurs. This operation is carried out by checking what are the lines which would be interconnected should the required connection be made, and whether the use of the transmission channels in the assembly of said lines, as it is in the initial state, will cause interference between the channels when the required connection is made.