This European Telecommunication Standard (ETS) defines the interface between the Subscriber Identity Module (SIM) and the Mobile Equipment (ME) for use during the network operation phase of GSM as well as those aspects of the internal organisation of the SIM which are related to the network operation phase. This is to ensure interoperability between a SIM and an ME independently of the respective manufacturers and operators. The concept of a split of the Mobile Station (MS) into these elements as well as the distinction between the GSM network operation phase, which is also called GSM operations, and the administrative management phase are described in the Technical Specification GSM 02.17 [6]. This ETS defines: - the requirements for the physical characteristics of the SIM, the electrical signals and the transmission protocols; - the model which shall be used as a basis for the design of the logical structure of the SIM; - the security features; - the interface functions; - the commands; - the contents of the files required for the GSM application; - the application protocol. Unless otherwise stated, references to GSM also apply to DCS 1800. This ETS does not specify any aspects related to the administrative management phase. Any internal technical realisation of either the SIM or the ME are only specified where these reflect over the interface. This ETS does not specify any of the security algorithms which may be used. This ETS defines the SIM/ME interface for GSM Phase 2. While all attempts have been made to maintain phase compatibility, any issues that specifically relate to Phase 1 should be referenced from within the relevant Phase 1 specification.