Universal Integrated Circuit Card is a Smart Card used in mobile terminals to ensure the integrity and security of the subscriber's personal data. Several application (SIM, USIM, CSIM ...) make it possible to give access to several networks with the same card.

The Universal Mobile Telecommunications System is one of the 3rd generation mobile phone technologies that allow a higher data rate than GSM does. Originally UMTS was standardised by ETSI but today it is supported by 3GPP.
UMTS uses usually W-CDMA as the the underlying air interface. The offered high data rate enables a connection to the World Wide Web as well as videoconferencing, chat, downloading music and video files, watch TV, navigation and further services.

The UMTS SIM Application Toolkit (USAT) is based on SAT but is enhanced for the features provided by the UMTS technology. It enables the USIM to drive the UMTS handset and enables an interactive exchange between a network application and the user. The USAT function is located on the USIM card.

A Universal Subscriber Identity Module (USIM) stores subscriber information, UMTS authentication information and provides storage space for text messages and phone book contacts.