A communications device for transmitting data to and receiving data from a mobile communications network, the mobile communications network including one or more network elements providing a wireless access interface for communicating with the communications device, the communications device comprising: a transmitter unit configured to transmit signals to the mobile communications network via the wireless access interface provided by the one or more network elements of the mobile communications network, and a receiver unit configured to receive signals from the mobile communications network via the wireless access interface provided by the one or more network elements of the mobile communications network, and a controller configured to control the receiver unit to receive one or more signalling messages from the mobile communications network, and the transmitter unit to transmit one or more signalling messages to the communications network, to establish a communications context for communicating data packets using a packet communications bearer from the communications device via the mobile communications network when operating in a connected state, the connected state being one of an ECM connected state and an RRC connected state, and to release the communications context and the packet communications bearer to an idle state, the idle state being one of an ECM idle state and an RRC idle state, characterised in that the communications device is configured to receive signalling information providing an indication of a plurality of power saving states (670, 672, 674), each of the power saving states providing an associated set of one or more functions, performed by at least one of the receiver, the transmitter or the controller, which can be changed to reduce power consumed by the communications device, and when in either the idle state or the connected state, to enter one of the plurality of power saving states in which the one or more of the operations performed by at least one of the receiver, the transmitter or the controller are configured in accordance with the indication of the changed functions received in the signalling information from the mobile communications network. a transmitter unit configured to transmit signals to the mobile communications network via the wireless access interface provided by the one or more network elements of the mobile communications network, and a receiver unit configured to receive signals from the mobile communications network via the wireless access interface provided by the one or more network elements of the mobile communications network, and a controller configured to control the receiver unit to receive one or more signalling messages from the mobile communications network, and the transmitter unit to transmit one or more signalling messages to the communications network, to establish a communications context for communicating data packets using a packet communications bearer from the communications device via the mobile communications network when operating in a connected state, the connected state being one of an ECM connected state and an RRC connected state, and to release the communications context and the packet communications bearer to an idle state, the idle state being one of an ECM idle state and an RRC idle state, characterised in that the communications device is configured to receive signalling information providing an indication of a plurality of power saving states (670, 672, 674), each of the power saving states providing an associated set of one or more functions, performed by at least one of the receiver, the transmitter or the controller, which can be changed to reduce power consumed by the communications device, and when in either the idle state or the connected state, to enter one of the plurality of power saving states in which the one or more of the operations performed by at least one of the receiver, the transmitter or the controller are configured in accordance with the indication of the changed functions received in the signalling information from the mobile communications network.