Technically, the UICC works in all mobile telecom networks. It is a type of smart card technology. Smaller in size than a full card, it contains a computer, or microprocessor, its own data storage and software. It is an evolution of the SIM used to identify subscribers in GSM networks. GSM, or Global System for Mobile Communications, is the most popular standard for wireless technology in the world with 3 billion users (41 percent of the population).
Like the SIM, the UICC has an application that stores your contacts and another that can help you optimize your call costs when roaming globally by maintaining a list of preferred networks in the UICC.
A big advantage of the UICC over the SIM, however, is it can have multiple applications on it. One of these, the USIM application, is what identifies you and your phone plan to your wireless service provider using one of these standards: Universal Mobile Telecommunications System (UMTS), High Speed Packet Access (HSPA) or Long Term Evolution (LTE). Another application, the CDMA SIM (CSIM), enables access to CDMA networks, which are different from GSM or UMTS networks. Other possible applications include ISIM, to secure mobile access to multimedia services, and non-telecom applications such as payment. In the United States for example, many subscribers have a UICC with USIM and ISIM applications for phone service and multimedia respectively.
Another advancement is that the UICC can communicate using Internet Protocol (IP), the same standard used in the Internet and the new generation of wireless networks. It also can support multiple PIN codes, which can better protect your digital life by preventing anyone from misusing personal information.