What Does A SIM Card Really Do?

Technology has allowed many people to connect with others all around the world. In fact, you can enjoy an amazing level of connectivity with a device that is only a bit smaller than your hand. When it comes to smartphones, one of the most basic kinds of connectivity they offer is a mobile network. This network can only be accessed with a SIM card.

These cards have revolutionized the way we use mobile devices. From allowing people to get in touch with their loved ones to elevating the accessibility of the internet, these are definitely an important aspect of mobile technology. Moreover, network providers have given users a whole lot of perks through these cards.


As a mobile phone user, you might be wondering about the actual functions of such cards. Sometimes it is nice to have a little bit of understanding of how the technology works. Check out the details below.

sim card

A Brief Background

Today, there are two types of phones: GSM and CDMA. SIMs came to be used in mobile phones back in 1992 when the global system for mobile, or GSM, devices emerged. Users will not be able to connect to any network using their GSM devices without inserting a SIM card first. Some examples of GSM networks are AT&T and T-Mobile.


On the contrary, code division multiple access, or CDMA, devices can connect to a particular network in which they are registered. CDMA networks maintain a list of all the phones that are allowed to access their network. In turn, phones that are associated with a CDMA carrier would not be able to connect to other networks. Sprint and Verizon are examples of this.

What Exactly Is A SIM?

Now that you know the origins of SIM cards, you might be curious about their function. Did you know that this word is actually an acronym? It stands for Subscriber Identity Module. By its name, it is easy to know that this small piece of plastic embedded with a chip serves as your individual ID in a mobile network.

As mentioned, SIMs lets you get in touch with people through a network. When you connect to your service provider’s network, your account appears using the identification info provided by your SIM. This allows you to successfully connect to the network. Then, you can do the usual things you do such as send text messages, make calls and use your data to connect to the internet.


What Does It Contain?

You have learned that a SIM serves as your individual ID that is used to connect to your provider’s network. It can do this by providing the network with essential information such as your International Mobile Subscriber Identity, or IMSI. This data is used by your service provider to connect callers to your device.

Aside from your IMSI, your SIM can also contain other info such as names, contact numbers, and messages. With SIMs, you can switch phones and still be connect to your network and access some of your contacts. However, remember that their capacity is extremely limited, which is why you can only store a few.

Other Things You Should Know

Nowadays, a lot of manufacturers are opting to use nano slots for your cards. However, this was not the case in the past. Many devices back then used full-sized cards which were around an inch in length. Then, came mini and nano cards. If you have been using your full-sized card for a long time and you want to switch to a more modern phone, there are tools that can help you cut your SIM down to the right size. However, you can also purchase cards that are pre-cut.


Should you wish to use more than one card, you can do so, as many newer models now have two SIM card slots. This is a great option for those who need to subscribe to two different networks at once. Moreover, you can also use your card in tablets. Just make sure that your device has a SIM card slot.

Now that you know how SIM cards work and how they function, you can better evaluate your options when choosing a network or a phone to purchase. With this, you can maximize the value of your money!

Last updated on November 17th, 2022 at 08:05 pm

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