Abstract: A method and apparatus are disclosed for transmitting in multi-channel fault-tolerant networks with bus, star, ring or mixed topology and multi-priority medium capacity distribution by medium idle time monitoring and changing station access numbers. Each station is connected with one or a plurality of communication channels and is assigned a unique set of initial access numbers. The current access numbers of each station are changed when a frame appears on the medium and restored to the initial values after transmission or reception of a network synchronization signal. Each station has a timer to monitor the idle time period when all input access lines of the station are quiescent. The timer starts when the medium becomes idle and stops if the medium becomes busy.