What is the difference between a SIM and a USIM? What is a UICC?
USIM (UMTS Suscriber Identity Module)
The role of the USIM is very similar to that of the SIM in GSM. Indeed, it is used to store subscriber identity, subscription data, authentication and ciphering keys as well as athentication algorithums. its security as well is improved compared to GSM with a mutual authentication between the card and the network.
A USIM contains the following information: language, application directory, Directory, IMSI MSISDN, TMSI, PTMSI, security keys, SMS parameters, service access, temporary id LAI/RAI, etc.
the interface between ME (Mobile Equipment) and USIM is the Cu interface, the importance of which is crucial for compatibility: even if full multi-mode terminals will not be developed (in a first period at least), USIM roaming will allow the subscriber to use different IMT-2000 terminals the same card.
UMTS Integrated Circuit Card (UICC)
The UICC is similar to an SIM card in GSM with the same size (either OSI or plug-in). It may contain one or several USIMs for different applications and also the SIM module in order to be used in a GSM terminal. Another possibility is to include additional mechanisms in the USIM part in order to provide the GSM access and be usable in a multi-mode UMTS/GSM terminal.
The Universal Integrated Circuit Card (UICC) is the removable card bearing a silicon chip which holds 3GPP system subscriber information. The UICC is a general purpose card having both non-volatile memory and a general-purpose processor. Thus while it is used, in a 3GPP terminal, to hold (U)SIM information / applications, it is can also be used for other purposes, possibly unrelated to telecommunications. A common use of UICCs is in the well-known credit card format, and there is no reason why a single card could not hold (U)SIM functionality in addition to electronic purse / credit card functionality, or indeed any other application / data. The Subscriber Identity Module (SIM) is the collection of functions which personalize a 3GPP terminal. The SIM contains static information about the services subscribed to, the phone number, the identity of the home network, a list of preferred roaming networks, and so on. The SIM also contains storage capacity for the subscriber’s contacts’ phone
