Subscriber identification cards

A subscriber identification card for use in conjunction with a mobile communications station operable in a mobile communications system, the card including a memory for storing data relating to records of telephone numbers of interest to the user and optionally corresponding contact names associated with such numbers and characterised in that the memory is configured and operable to store additional data useful to the user in operation of the mobile station other than telephone names and contact numbers. Also described is a method of storing information of a user of a mobile station operable within a mobile communications system which includes connecting the subscriber identification card to the mobile station, entry by the user of data into the mobile station via a user data input interface, transfer of the data to the card and insertion of the data into the memory of the card for storage therein, wherein the data includes data useful to the user in operation of the mobile station other than contact names and telephone numbers. The mobile station may be operable in a GSM or TETRA system operating in trunked and/or direct operational mode.