A terminal device includes receiver circuitry that receives parameter data from a base station in a cellular wireless telecommunication network. The terminal device also includes a storage device that stores an identifier that uniquely identifies the terminal device, and control circuitry that controls the terminal device. The control circuitry controls the terminal device, when operating in an idle mode, to perform cell reselection using at least one cell reselection parameter derived from the received parameter data and the stored unique identifier.