The present document relates to radio transmission. In particular, the present document relates to the single-slot dual transfer mode (DTM) available e.g. in GSM/GPRS/GERAN networks. A transmitter is described. The transmitter is configured to send circuit switched data over a traffic channel to a corresponding receiver, wherein the traffic channel is segmented into a plurality of frames. The transmitter if further configured to determine a vacant frame of the plurality of frames, wherein no circuit switched data is sent in the vacant frame due to discontinuous transmission; and to send packet switched data over the traffic channel using the vacant frame.