The invention relates to a communication method for a digital cellular mobile telephone system and a digital cellular mobile telephone system comprising several base stations and mobiles utilizing time division multiple access. In the system communication is carried out on a predetermined frequency band in a predetermined number of time slots having a predetermined length. In the communication between the mobiles and the base station within the TDMA time slot with the predetermined length, the transmissions to communicate information comprising a few bits or several bits from the mobiles communicating with the same base station at least within the same time slot are mutually substantially orthogonal. Preferably, in order to communicate information, preferably information of the on-off type, such as acknowledgments and channel allocation requests, the mobiles communicating with the same base station use substantially orthogonal transmissions at least to the same base station in the same time slot. Preferably each mobile transmits within the TDMA burst of said TDMA time slot of the predetermined length as a part of the burst a predetermined bit sequence corresponding to the transmitted information bit combination, whereby the predetermined frequency band is unchanged. The bit sequences transmitted by different mobiles to the same base station are mutually substantially orthogonal. By using such substantially orthogonal transmissions it is possible to avoid collisions between the communications of information comprising a few or several bits, typically 1 to 10 bits, such as acknowledgments and channel allocation requests, which typically occur in a time division multiple access system.