I've browsing through some jargon and cannot figure out what exactly the difference is between USIM and SIM. While not strictly an android question I figure all android phones are bound to have either one or the other so any clarification on this issue would be greatly appreciated.

2 Answers 2


SIM is a old guy, but USIM (card's name is UICC, USIM is logical module) is new designed specially for UMTS (3G) generation. While SIM can also be used to access 3G, USIM has extra advantages over SIM:

  • 3G Video Calls (not supported with SIM)

  • Higher Security: USIM introduces new algorithm to prevent unauthorized access to phone line. Plus, it encrypts your calls and internet traffic with stronger encryption keys. It stores contacts securely too.

  • Bigger and Improved phonebook: USIM allows you to store thousands of contacts (limit on SIM is 255). Each contact can now contain email id and more than one phone number.

  • USIM can run small applications like computer (SIM's analog is simple SIM menu which can't compute something by own other than communicating with carrier's server).


USIM could mean one of two things.

  1. Universal Subscriber Identity Module, which refers to the software that runs within the SIM card (technically now called a UICC (Universal Integrated Circuit Card) in UMTS parlance).
  2. uSIM could also mean microSIM (using u rather than μ), a SIM card format (technically known as 3FF) smaller than the miniSIM (2FF) used in most devices.

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