A method and a device for transferring signalling information in a TDMA based system. Temporal alignment of values for a retransmission number parameter (R) with the TDMA frame structure is determined on the basis of which a first radio packet to be sent in a number of first TDMA frames is encoded by using a certain first value for the parameter and a second radio packet to be sent in a number of second TDMA frames is encoded by using a certain second value for the parameter. The first and second radio packets are transmitted to the recipient that adheres to the same temporal alignment rules and can thus properly decode both the packets. The solution can be utilized especially in GERAN radio access network with FLO (Flexible Layer One) for transferring signalling information on half-rate channels.