What is a SIM card?

A SIM card stands for Subscriber Identity Module. SIM cards are small circuit chips that your mobile device uses to communicate information and network coverage to your carrier’s cell towers. They come in a variety of sizes depending on the device, including Standard (15 by 25 mm), Micro (12 by 15 mm) and Nano (8.8 by 12.3 mm).

Your SIM card may store information about you, especially if your cell phone carrier is on a GSM network.

This information may include:

  • Your International Mobile Subscriber Identity, which allows the network to know it’s your device
  • Where you’re located, down to the communication points between cell towers
  • Your contacts, especially if your phone is an older model

LTE also utilizes SIM cards, so even phones that use a CDMA cellular network may utilize a SIM card to access LTE coverage.