A terminal device, operable in a wireless telecommunications system, including: a receiver operable to receive a first control message from a base station indicating a radio resource for use by at least one of the receiver and a transmitter to exchange a signal with a base station, the first control message including a code generated based on an identifier of an intended terminal device and a value of a time-dependent parameter at a transmission time. The controller is operable to: attempt to perform a predetermined process using the code, an identifier of the terminal device, and the value of the time-dependant parameter; wherein: if the predetermined process is not successfully completed, disregard the first control message; if the predetermined process is successfully completed, control at least one of the receiver and transmitter to exchange a signal with the base station using the radio resource indicated by the first control message.