What Information Is Stored on A Sim Card? [Types of Sim Cards]

Sim cards are some of the most important things to have as they connect you to your loved ones and the internet. Without them, your phone is useless. That tiny card is the key to the internet and unlimited, real-time communication.

If you’re wondering how it does so much when it’s so little and what information is stored on a sim card, we are here to provide answers. After reading this article, you would get to know a lot more about sim cards and how they work.

What Information Is Stored on A Sim Card?

The information stored on a sim card includes contacts, messages, user identity, phone number, location, network authorization data, personal security keys, billing information, and data usage. The storage capacity of a sim card ranges from 32kb to at least 256kb, and it can store up to 500 contacts depending on the storage capacity. Nowadays, people prefer to store their contacts on the cloud – especially iPhone users.

With an iPhone, your contacts and messages will be automatically saved to the cloud instead of your sim card, some people find this a safer option because one can easily lose a sim card and all the information on it. Sim cards are also a major target for hackers because of the personal information stored on them. Your sim card and phone number can also be used to get into your bank account, so it is essential to keep it safe. So, the answer to what information is stored on a sim card is basically, a big chunk of your personal information.

Types of Sim Cards

There are Full size, Mini, Micro, Nano, and Embedded sim cards. These are the different sizes that a sim card can come in.


The ‘Full size’ sim card is more outdated and was used in larger phones, no modern phone uses this type of sim card. Its dimensions are 12.3mm × 8.8mm.


The ‘Mini’ sim card is also outdated and the largest sim card size available in recent times, it is typically used in older basic cell phones. Its dimensions are 25mm x 15mm.


The ‘Micro’ sim card is more recent and mostly used with devices like tablets, some older android phones, and routers. Its dimensions are 15mm x 12mm.


The ‘Nano’ sim card is the smallest, most recent, and most popular sim card size available today. It is used in the majority of devices. Its dimensions are 6mm × 5mm. A lot of smartphones are yet to adopt this technology, so it can mostly be found in vehicle cameras, drones, and home alarms.


The ‘Embedded’ sim is built into devices and eliminates the need for a physical sim. This way, you would not lose your sim and it cannot be stolen unless your phone itself is stolen.

When getting a sim card, it is important to consider where you want to use it and what size of sim card the device supports. However, sim cards have evolved and you can get all three sizes in one sim card. These are the ‘Combi’ sim cards, they can be used in either size by removing the excess surrounding plastic.

Read also: What Does SIM Failure Mean? 

Which Part of a Sim Card Is for the Internet?

Your phone connects you to the internet using the IMSI number and authentication key provided by your sim card. First, when your phone is turned ON, it starts to search for a network to connect to. Once a network is found, it begins trying to connect to the network by sending your IMSI number and unique authentication key to the network tower.

The network tower receives it and tries to check your identity and if you are authorized to use the network, so it scans through the database for your IMSI number. The IMSI number has an authentication key assigned to it in the database, so the network will search for this too. Once it finds you in the database, it will authenticate you using the authentication number assigned to your IMSI number in the database, and then generate a random key of its own.

Then it sends the authentication key assigned to your IMSI number and the random key is generated to your phone. Your phone will then scan both keys and create another key, then send it along with the same authentication key back to the network tower. The network will then analyze the new key and the authentication key, then using the same authentication key, it will compare the random key it generated earlier and the key your phone generated.

Both keys must match, if they do, your phone will be granted access to the internet and locked in. This process is necessary for safe and secure browsing of the internet.

Read also: Why Is My SIM Card Not Working?

Does A Sim Card Hold Pictures?

No, a sim card does not hold pictures. Sim cards were used to store pictures back in the day but with higher resolution cameras, there isn’t enough space on a sim card to hold even one picture. And with increased information for contacts, most recent phones store contacts directly on the phone or in the cloud instead of the sim card.

What Can Someone Do with Your Sim Card?

If in the wrong hands, your sim card can be used to gain access to your bank account, your personal information, and receive/send calls and messages. They can also use services that will be billed to you. Sim cards typically have a pin for security purposes, however, hackers can be pretty good at guessing them. If you notice that your sim card has been stolen or lost, contact your network provider immediately to prevent a hack into your account.

Read also: If I Put My SIM Card in another Phone What Will Happen?

Sim Card Parts and Functions

The parts of a sim card and their functions include;

  1. VPP (Voltage Programming power)
  2. VCC (Power supply)
  3. CLK (Clock)
  4. RST (Reset)
  5. Sim Data I/O pin
  6. GND (Ground)
  7. D+ and D- (Optional USB Pad)

The functionalities of a sim card include authentication, identification, worldwide connectivity via roaming, internet connectivity, and storage.


Now that you know what information is stored on a sim card, you should also know how important it is to keep it safe and what to do in the event of losing it.