3GPP42.017Functional characteristicsSubscriber Identity Module (SIM)TS
A GSM MS comprises an ME and a SIM. The SIM is a removable module. The SIM contains the International Mobile Subscriber Identity (IMSI) which unambiguously identifies a subscriber. Without a valid IMSI, GSM service is not accessible (except emergency calls, as defined in GSM 02.03 ).
The user interface (MMI) of the ME related to SIM operations is defined in GSM 02.30 .
GSM 02.09  specifies a security function for authenticating the SIM. This function, which is mandatory for any MS, is based on a cryptographic algorithm, A3, and a secret subscriber authentication key, Ki, both of which are located in the SIM.
The SIM provides storage of subscriber related information. This data is of three types:
– data fixed during administrative phase; e.g. IMSI, subscriber authentication key, access control class;
– temporary network data; e.g. TMSI, LAI, Kc, Forbidden PLMNs;
– service related data; e.g. Language Preference, Advice of Charge.
The SIM contains Card Holder Verification information (CHV1 – see clause 5) to provide protection against unauthorized use. For some optional features, the use of a second CHV (CHV2) is required. CHV(s) shall be stored and verified within the SIM.
The SIM may also contain applications which use the features defined in the SIM Application Toolkit specification GSM 11.14 
Two physical types of SIM are specified. These are the "ID‑1 SIM" and the "Plug-in SIM".
The physical characteristics of both types of SIM are defined in GSM 11.11 .
The logical and electrical interface of the SIM is defined in GSM 11.11  and GSM 11.12  and is identical for both types of SIM.
The information on the exterior of either SIM should include at least the individual account identifier and the check digit of the IC Card Identification (see CCITT Recommendation E.118 ).
4.1.1 ID‑1 SIM
Format and layout of the ID‑1 SIM shall be in accordance with ISO 7816‑1, 2 [13, 14]. The card shall have a polarization mark, as defined in GSM 02.07 , which indicates how the user should insert the card into the ME.
SIMs may be embossed (see GSM 11.11 ).
4.1.2 Plug-in SIM
The Plug-in SIM is smaller than the ID‑1 SIM and has dimensions as defined in GSM 11.11 . It is intended to be semi-permanently installed in the ME.
4.2 Phases of operation
4.2.1 Administrative management phase
GSM administrative management phase may be entered at any time, to bring in or change data not accessible by the subscriber in GSM operational phase. Only by specific administrative authentication mechanisms and commands can the administrative phase be entered and administrative functions be performed. The specification of administrative operations and the parties responsible for them are outside the scope of the present document.
The different types of administrative phases which may occur during the lifetime of a SIM are:
Following production a SIM contains at least the authentication algorithm and the operating system necessary for (pre)personalization.
Prepersonalization, personalization and repersonalization are processes during which subscription data, e.g. IMSI, and subscriber data are entered into or updated in the SIM. The split between these processes and adoption of appropriate security measures is dependent upon the chosen administrative management structure.
For example, the following parties may have responsibilities during the administrative phase as follows:
– SIM manufacturer: card production.
– SIM issuer: SIM configuration.
– Service activator: activating the SIM on the GSM network.
– Delivery party: programming of subscriber data and distribution of card to subscriber.
These parties may be separate organizations or combined, and the activities merged; e.g. SIM issue, Service Activation and Delivery may all be the responsibility of a network operator.
4.2.2 GSM network operation phase
Once a SIM has been personalized with all data required for GSM network operation, the GSM network operation phase is entered.