A wireless telecommunications system comprises a base station and a terminal device. The system supports a virtual carrier mode of operation in which downlink communications are made by the base station using a radio interface that spans a system frequency bandwidth while the terminal device is configured to receive at least some communications from the base station within a restricted subset of transmission resources selected from within the system frequency bandwidth. The wireless telecommunications system supports terminal devices in both a radio resource control connected mode and a radio resource control idle mode. When there is to be a change in system information the base station transmits to the terminal device an indication that updated system information is to be broadcast by the base station and this indication is received by the terminal device while in the connected mode. Before seeking to acquire the updated system information, the terminal device transitions from the connected mode to the idle mode. The terminal device then seeks to acquire updated system information while in the idle mode. The base station restricts the transmission of user-plane data to the terminal device until the terminal device re-enters connected mode. Transitioning to idle mode to acquire system information can help to address issues associated with managing the communication of both system information and user-plane data using the restricted subset of transmission resources.