
Muninder Adavelli
Updated · May 30, 2023
Velina describes herself as passionate media savvy and a versatile individual with numerous differen... | See full bio
Your phone has died and now need to take out that small thingy with a chip and put it on another phone. That tiny bit of plastic you’re transferring is your SIM card.
If you want to find out how it works and what is stored on a SIM card, read on.
But, first:
The full name of the SIM card - Subscriber Identity Module - reveals what it actually is. To mobile networks, we are all subscribers. They use SIM cards to identify our phones and the activities we perform on them.
So, the portable memory chip you’ve taken out of your device is the ID card of your phone. It contains printed integrated circuits with a seventeen-digit number. This code is unique. It designates the country, carrier, and user of any mobile phone.
There is also a variety of information on the SIM card such as who is paying for the access and the permission to use the features like making and receiving a call or a text message.
Insert the SIM card in its designated slot, wait for the phone to connect to a mobile network and you are good to go! Of course, you need to see first if the carrier identifies whether your phone can operate on their network. This is basically what SIM cards are used for.
In many countries, mobile companies lock their SIM cards and devices. So, if you purchase your phone and SIM card from the same carrier you have access to all features. If not, you can’t place any calls or send any texts on the network except emergency calls. It’s possible to unlock your cell with permission from the cellular operator.
SIM cards are also important to mobile providers. Besides its primary SIM card function to identify its users and route calls, phone companies track your phone usage. The minutes, texts, and data utilization are measured so that carriers can charge you for their services. They can also turn them off if you don’t pay your bills. Hence, you can have a SIM card properly placed but your phone won’t work.
SIM cards can save only a certain number of your contacts and some text messages. But, there is more to it.
Here is the other information stored on your SIM card:
This seems like a lot of information and you’re probably asking yourself:
SIM card storage capacities are not that big and usually range from 8KB to 256KB or 512KB for newer cards. The SIM card contains your key data plus around 250 contacts and some messages.
However, you can’t use it as a memory bank. If you need extra space you need to install a micro-SD card (if it’s supported on your phone).
To see SIM card data on your Android phone, go to Settings and tap “About phone”. You can also search “About phone” and then choose “Status” and “SIM status” to see your network, roaming info, signal strength, and more.
On an iPhone, you can go to Settings, then choose “Cellular” and “Celular Data Option” to see info on your SIM card. There is also an option to see if any apps are using storage on your SIM card by choosing SIM Applications in Settings.
If you want to see precisely what’s on your card, you can even buy a SIM card reader. That’s a separate piece of hardware used for transferring SIM card info to your computer for further inspection.
Your SIM card is not immune to hacker attacks. An average person uses a SIM card to place and receive calls and send text messages. Then, you might ask yourself, why do fraudsters need it? They are after your phone number which is often linked to your email, social media accounts, and banking details.
There isn’t one, but three different ways to get your SIM card hacked:
One way to compromise your SIM card is to clone it. For this hack, someone has to have physical access to your original card. They use smart card copying software to transfer all your SIM card data onto a duplicate. With it, they can make calls and send messages in your name.
Cybercriminals can also send a spyware-type code to your phone in a text message. When you open it, the hacker gets access to your calls and messages. They can utilize your phone apps and see your passwords which they can later change to new ones. Your bank account is the first target on their list.
This is another way cybercriminals pretend to be you. They call your cell phone operator convincing them to change the SIM. Then they transfer your SIM card details to another card, getting access to your text messages. Fraudsters can reset passwords through a text message and your bank account is once again at high risk.
Well, now you know what information your SIM card contains and what it is used for.
SIM cards might be a 30-year-old technology but they are here to stay.
For how long? We’ll see.
The SIM card memory is not enough to save your pictures. It stores a small amount of info including:
Your photos are not on the card, so it’s best to do some kind of backup.
Your contacts are not automatically saved on your SIM card. You need to choose that option manually when saving a new number or copying it. And this is only possible on Android devices. iPhones don’t have that option.
Typically, what is stored on a SIM card are messages and some data. Contacts are saved directly in the phone’s internal memory. Additionally, they can be synced with cloud servers or saved on your Google or Apple accounts.
No. If you want to see your browsing history, you can only do that on the search engine you used (Google Chrome, for example).
Velina Nenova
Velina describes herself as passionate media savvy and a versatile individual with numerous different interests, most a result of her Media & Communications BA. She has also developed a keen interest in Digital Marketing and Advertising. Her never-ending desire to constantly learn new things and enrich herself and her ultimate dream to go around the globe before 45 are her driving forces.
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