This European Telecommunication Standard (ETS) defines the functional characteristics and requirements of the Subscriber Identity Module (SI M) for use in GSM and DCS 1800 applications. All references to GSM sh all apply equally to DCS 1800 unless otherwise stated. The SIM is the entity that contains the identity of the subscriber. Wh en placed in a Mobile Equipment (ME), together they become a Mobile St ation (MS) which may then register onto a GSM network. The primary function of the SIM in conjunction with a GSM network is t o authenticate the validity of an MS when accessing the network. In ad dition it provides a means to authenticate the user and may also store other subscriber-related information. Subscription entitlements are s tored 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 th e case of multi-application cards, this ETS defines just the GSM appli cation.