A method for controlling the retransmission of data units in a wireless telecommunication system, comprising the steps of: receiving a plurality of data units from a transmitter at a receiver; in response to the receipt of each of said plurality of data units, attempting to decode said data unit at said receiver, and: if said data unit is successfully decoded, transmitting positive feedback from said receiver to said transmitter, said positive feedback indicating to said transmitter that said data unit was successfully decoded by said receiver; or, if said data unit is not successfully decoded, transmitting negative feedback from said receiver to said transmitter, said negative feedback indicating to said transmitter that said data unit was not successfully decoded by said receiver; selecting a first radio channel for transmitting said positive or negative feedback, wherein said first radio channel differs from a second radio channel at least in terms of channel characteristics; and transmitting (402, 405) a Status Message on said second radio channel from said receiver to said transmitter, said status message comprising explicit information identifying one of said plurality of data units; the Status Message is transmitted on the second radio channel using a transmission method that is more reliable than a transmission method used on the first radio channel to ensure that the Status Message is correctly interpreted at the transmitter, and the method characterised in that said Status Message comprises a Cyclic Redundancy Check, CRC, value whereby said transmitter can verify that said Status Message is correctly received. receiving a plurality of data units from a transmitter at a receiver; in response to the receipt of each of said plurality of data units, attempting to decode said data unit at said receiver, and: if said data unit is successfully decoded, transmitting positive feedback from said receiver to said transmitter, said positive feedback indicating to said transmitter that said data unit was successfully decoded by said receiver; or, if said data unit is not successfully decoded, transmitting negative feedback from said receiver to said transmitter, said negative feedback indicating to said transmitter that said data unit was not successfully decoded by said receiver; if said data unit is successfully decoded, transmitting positive feedback from said receiver to said transmitter, said positive feedback indicating to said transmitter that said data unit was successfully decoded by said receiver; or, if said data unit is not successfully decoded, transmitting negative feedback from said receiver to said transmitter, said negative feedback indicating to said transmitter that said data unit was not successfully decoded by said receiver; selecting a first radio channel for transmitting said positive or negative feedback, wherein said first radio channel differs from a second radio channel at least in terms of channel characteristics; and transmitting (402, 405) a Status Message on said second radio channel from said receiver to said transmitter, said status message comprising explicit information identifying one of said plurality of data units; the Status Message is transmitted on the second radio channel using a transmission method that is more reliable than a transmission method used on the first radio channel to ensure that the Status Message is correctly interpreted at the transmitter, and the method characterised in that said Status Message comprises a Cyclic Redundancy Check, CRC, value whereby said transmitter can verify that said Status Message is correctly received.