SIM Cards: What are They Anyway?

We all know we need a SIM card in our phones in order to use it for phone calls and to save contacts. But is there more to them than that? What are SIM cards, anyway? We’ve got the low down.

What is a SIM card?

SIM, or subscriber identity module, is a piece of plastic that slots into your phone and acts as a unique identity number. This allows you to connect to, make calls from, and be charged for using the services of any given mobile network. Without one, you will not be able to get in touch with anyone (other than emergency services), or use the internet in any way.

How did they come to be?

SIM cards originated as part of the European telecoms standard that was used to separate phones from the networks they were connected to. How they did this was by migrating the security and identity features and data onto a small chip that could be embedded into the phone itself. SIMS were used to unlock the data, like a decryption device.

What else do they do?

SIM cards store your contacts as well as their numbers allowing you to switch phones without having to reload them all. They may be small, but they are mighty, indeed!

Now that you have the knowledge, it’s time to shop for your new smartphone! Head to or your Gumtree app (click for Apple & Android).

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