A plurality of subscriber units are connected to at least two transceiver stations for exchanging information in a time division multiple access mode, in which traffic time intervals are allocated in rotation to a variable number C of channels, where C is dependent on the number and type of units to be connected. T intervals plus one control time interval form a frame, where T is mutually prime with respect to the numbers 2 through C.sub.MAX. M frames form a superframe, where M is the lowest common multiple of the numbers 1 through C.sub.MAX.