Abstract: In a message transmission network of CSMA-CD type, each station is connected by a coupler to the common transmission channel. One or more indices is allocated to each coupler; and each coupler is provided with an automatic device capable of establishing a predetermined sequence of index sub-sets, such as a dichotomous tree. A counter of period E progresses at the rate of the end of channel phase orders. The coupler freely transmits only if its count E is at zero. When a collision appears in this state, the counter E starts from a chosen forced state, and all the couplers put their automatic devices into action, which also progress at the rate of the ends of channel phases, to establish sub-sets of said sequence and to determine, by comparison of their own indices with said sub-sets, whether they have in any given channel phase again obtained the right to transmit on said common channel. The couplers will subsequently be able to transmit one by one without collision.