Print Friendly, PDF & Email

SIM cards

Facts for Prelims (FFP)


Source: TH


Context: The growing use of mobile phones have highlighted the importance of SIM cards, or Subscriber Identification Module cards, which are essential components for connecting mobile phones to cellular networks following the GSM standard.

  • The SIM card contains information, such as the International Mobile Subscriber Identity (IMSI), the subscriber’s location, a list of preferred networks for roaming, emergency numbers, and, space permitting, the subscriber’s contacts and SMS messages.
  • SIM cards adhere to international standards (ISO/IEC 7816) maintained by organizations like the International Organization for Standardization.




The SIM card hardware features an integrated circuit connected to metal contacts on the card’s surface. These contacts serve specific purposes, like power supply, clock access, data transmission, and grounding, as defined by ISO/IEC 7816-2. The SIM card plays a crucial role in authenticating a phone’s place within a cellular network.


Evolution of SIM cards:


SIM cards have evolved in size, from full-size SIMs to nano SIMs. The latest development is the eSIM (eUICC), where the SIM software is preloaded onto the mobile equipment, eliminating the need for a physical card.

This reprogrammable eSIM is environmentally friendly and enhances security, as it is not physically removable, making it harder for malicious individuals to access the SIM application. However, it can potentially allow network operators to track users’ data more comprehensively, even within apps on the device.