Difference between SIM and USIM Card

Key Difference: SIM (Subscriber Identity Module) is a memory chip used in mobile phones. The term SIM is used to denote a 2G application. USIM (Universal Subscriber Identity Module) card is also a SIM card for 3G services. USIM provides enhanced features than compared to SIM like enhanced security, etc.

SIM or Subscriber Identity Module is a microprocessor chip which is used in mobile phones. USIM or Universal Subscriber Identity Module is also a type of SIM card but specifically for WCDMA/UMTS (3G) phones. SIM refers to a 2G application which was introduced during the initial or early days of GSM standards, later with the introduction of 3G applications, more complex functions also get coupled with the card and SIM got evolved into USIM.

SIM cards play a vital role in mobile industry as they are used to access a GSM network. USIM cards are used for accessing 3 G networks. It does not means that a simple SIM cards cannot be used in place of USIMs for accessing a 3 G network. Usage of USIM also provides some added advantages, and therefore one prefers to use USIM over SIM for accessing a 3 G network.

SIMs are basically Universal Integrated Circuit cards (UICC) which contain both account information and memory. USIM cards store subscriber information and authentication information. It also provides storage space for text messages and phone book contacts.

Due to the advanced technology applied in USIM architecture and operating system, secure and complex applications related functions can be performed. Examples of such applications include mobile banking, video conferencing, enhanced phonebooks, mobile bookmarks etc.

SIM offers a global phone book, whereas USIM offers global phone book and hidden phone book. SIM cards are capable of providing a phone book with limited capacity which is 32 k or 64 k. On the other hand, USIM cards have an extended phone book (256 k). USIM also provides some features which are not available in other SIMs like – APN settings can be written directly on to the USIM card and MMS can also be stored on a USIM card. USIM make use of a new algorithm which protects from unauthorized access to one’s phone line. Encrypted calls and data exchanges of USIMs make use of strong keys than keys used by SIMs.

Comparison between SIM and USIM Card:

	SIM Card	USIM Card
Full Form	Subscriber Identity Module or Subscriber Identification Module Card	Universal Subscriber Identity Module
Definition	SIM is a memory chip which is used in mobile phones. It stores data for GSM/CDMA Cellular telephone subscribers.	USIM card is the logical extension of the SIM card specifically designed for 3G environment.
Phone book	Global phone book	Global phone book and hidden phone book
Compatibility	Compatible with 3 G	Backward compatible with 2 G GSM technology
Security	A5, A3 and A8 algorithms are not very secured	Comparatively more secured :Milenage and kausami Algo’s
Phone Book	Limited phone book (32 K or 64 K)	Extended Phone book (256 K)