An electronic device such as a mobile telephone is provided with a reader for reading data from a physical data carrier. Physical data carriers are incorporated into accessories of the device, for example a telephone carrying case. The act of inserting the telephone into the case causes the reader to read data from the data carrier and the data is used to implement required device settings of the electronic device. The data carrier may be a bar code, RF tag or contact tag. By providing a number of carrying cases each with its own data carrier, merely exchanging cases initiates a number of associated device settings to be selected. Each case may be associated with a particular environment or user context allowing the user to alter the behavior of the device to suit context merely by interchanging carrying case. Data carrier may also be provided in other accessories such as car-telephone kits and battery chargers to alter device behavior accordingly. Device settings include those which govern the type of information relayed to the user when the device receives information from data delivery services.