A method of operating a terminal device in a wireless telecommunications system is disclosed. The terminal device is configured to selectively switch between an active operating mode and a reduced-power operating mode. The method comprises communicating with a network entity to exchange a block of data between the terminal device and the network entity while the terminal device is in the active operating mode. The method further comprises determining when communications associated with the exchange of the block of data are complete, and in response to determining communications associated with the exchange of the block of data are complete, switching from the active operating mode to the reduced-power operating mode.