What is a SIM Card and How Does it Work?

Have you ever handled a mobile phone then you have probably heard of SIM cards, but what is it really? Simply put, it can be described as a small circuit board that acts as an intermediary between your mobile phone and your telephone company.

It is the SIM card that allows your mobile phone to communicate with the mobile antennas provided by the telephone company where you have your subscription. SIM cards also sit in iPads and tablets and perform the same function there.

SIM stands for Subscriber Identification Module, which can be freely translated into the Subscriber Identification Module for Subscribers. In addition to the SIM card enabling communication, it also contains the most basic parts of your user data.

It contains information such as your telephone number and data that allows your telephone company to identify your subscription, which determines how much it costs when you call or send SMS.

Since the SIM card identifies you as a customer, it is also what enables you to change mobile phone without having to change mobile subscriptions at the same time. You simply move the SIM card from your old mobile to your new one and continue to call for the same costs and terms that apply in your subscription.

You get a SIM card when you get a mobile subscription

A SIM card is not something you need to purchase separately. When you sign up for a new mobile subscription, the operator will send you a new SIM card which you can then insert into your mobile phone yourself.

How to remove and insert your SIM card

Exactly how to change SIM card varies slightly depending on which phone or tablet you have. But the differences between the various units are usually delicate. For example, exactly where you find the SIM card may vary. The two most common options are that you find the SIM card either in a smaller slot on the side of your phone or tablet, or alternatively it sits in a small metal bracket behind the battery in your device.

You can easily check what applies to your particular device by looking in the instruction manual. Alternatively, look for a smaller run on the side of the unit. The only tool you need to be able to remove or insert a SIM card is usually no more than a regular paper clip or similar, long, narrow and sturdy object.

If the SIM card is in a slot on the side of your device

  • Turn off your mobile phone or tablet.
  • Use a paper clip or similar narrow object and squeeze into the hole next to the slot where the SIM card is located to push out the tray holding it.
  • Remove the SIM card.
  • Follow the steps above for the device where you want to insert your SIM card. Insert the SIM card and boot the device.
    If the SIM card is under the battery of your device
  • Make sure the unit is turned off.
  • Carefully remove the back cover.
  • To lift the battery, gently push it down from the bottom and lift it up.
  • Under the battery, you will find the metal bracket that holds the SIM card. Insert your new SIM card or lift out the old one.
    After inserting a SIM card, insert the battery and put the cover back on, you can turn on the device.


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