This European Telecommunication Standard (ETS) defines the functional characteristics and requirements of the Subscriber Identity Module (SIM) for use in GSM and DCS 1 800 applications. All references to GSM shall apply equally to DCS 1 800 unless otherwise stated. The SIM is the entity that contains the identity of the subscriber. When placed in a Mobile Equipment (ME)@ together they become a Mobile Station (MS) which may then register onto a GSM network. The primary function of the SIM in conjunction with a GSM network is to authenticate the validity of an MS when accessing the network. In addition it provides a means to authenticate the user and may also store other subscriber-related information. Subscription entitlements are stored not in the SIM@ but in the network. If the SIM functionality is incorporated into a multi-application ETSI/TE9 card@ the GSM application may be used in other telecommunication applications. In addition SIMs are permitted to contain non-GSM functionality. In the case of multi-application cards@ this ETS defines just the GSM application.