Signalling information is conveyed from a transmitting device (101) to a receiving device (102) in a cellular radio network where user data transmission takes place on a traffic channel in discrete transmission bursts (111-120; 211-220; 310-313) consisting of consecutive symbols. A piece of signalling information is formatted into symbols which are transmitted as a block of consecutive symbols (FACCH) in a certain transmission burst of a traffic channel. It is also indicated within said certain transmission burst that it contains symbols carrying signalling information.