User Services Identity Module (USIM) is the name of the logical module in the Universal Integrated Circuit Card (UICC) designed specially for 3G or Universal Mobile Telecommunications System (UMTS). There is a common misconception to call the UICC itself a USIM, but the USIM is merely a logical module in the UICC (physical card). UICC is usually made of PVC with embedded contacts and semiconductors. The primary function of USIM is to secure the authenticity of the mobile station with respect to the network and vice versa. USIM supports 2G, 3G, 4G networks. A normal SIM can also be used to access 3G, but USIM has extra advantages like enhanced security, executing programs with protection against manipulation, bigger and improved phone-book etc.