What is Stored on a SIM Card? [All You Need To Know]

Have you ever thought about what's on your phone's SIM card? It's more than just a means to connect to phone networks—it contains much more than you think.

With a staggering 7.8 billion active SIM cards worldwide, it is surprising how only a few people understand what a SIM card is and what’s stored in it.

In this article, we'll explore the hidden depths of SIM card data storage and shed light on its capacity and workability.

Data Stored on a SIM Card

Subscriber Identity Module (SIM) cards store various information, including your phone number, contacts, and text messages. It also holds data identifying your network, such as your number and the authentication key used to access it.

The exact data stored on a SIM card can vary depending on your carrier and phone model. But here are the data stored on a typical SIM card and their function:

With so much information a SIM card can hold, you’ll expect it to contain a lot of storage, but that’s not the case. Continue reading to learn more about a SIM card's storage capacity.

SIM Card’s Storage Capacity

A SIM card storage capacity is typically between 8KB and 256KB or 512KB for more recent cards. This storage capacity can hold up to 250 contacts and some messages. 

How Does a SIM Card Work

A sim card lets your phone connect to your carrier network and provides information about you and your location. This process will enable you to make calls, send texts, and use mobile internet data

Although sim cards might seem inexpensive, without them, your smartphone won't be able to do anything on a network except for emergency functions. 

The unique identifier on a SIM card also gives carriers some control over users who do not pay their bills. A carrier can turn off service, causing a phone to stop working even if the SIM card is inserted.

Types of SIM Cards

Since the SIM card's introduction in 1991, mobile technology has changed rapidly, necessitating hardware modifications and resulting in five main varieties of SIM cards. These are:

• Full size- The oldest type of SIM card with the size of a credit card. Its dimensions are 85.60mm × 53.98mm × 0.76mm.
• Mini - This type of SIM card is also called the standard SIM card or regular SIM card size. The dimensions of the mini-SIM are 25mm x 15mm x 0.76mm.
• Micro- Smaller than mini-SIM, this SIM card is used in many latest Smartphones. The dimensions of the microSIM card are 15mm x 12mm x 0.76mm.
• Nano- The smallest available SIM card out today. The dimensions of nano SIM are 12.3mm x 8.8mm x 0.67mm.

Checking What’s on Your SIM Card

With vital information stored in a SIM card, it’s also essential to know how to check its content. Here are methods to view SIM card information on Android and iPhone devices.

Android

To view SIM card information on an Android,  do the following:

Step 1. Navigate to Settings and select About Phone.

Step 2. Search About phone and then select Status.

Step 3. Click SIM status to view your network, roaming information, signal intensity, and other information.

Iphone

If you are an  iPhone user, these are steps to view what’s in your SIM card:

Step 1. Go to Settings, then select Cellular.

Step 2. Click Cellular Data Option.

Step 3. Check if any applications are utilizing storage on your SIM card by selecting SIM Applications in Settings.

You can even purchase a SIM card reader. This hardware can transfer SIM card information to your computer for further examination.

Security Risk in a SIM Card 

Many people are unaware that even SIM cards can be hacked. In November 2022, T-Mobile reported that approximately 37 million subscribers' personal information was exposed due to an API data breach.

From social engineering scams to SIM hijacking, sensitive data can quickly become compromised without adequate cybersecurity awareness.

Learn more about the different types of SIM card hacking and how to prevent it.

• SIM Cloning

Cloning is one method for hacking a SIM card. For this to happen, physical access to your original card is required. 

Hackers use intelligent card duplication software to copy all the information from your SIM card. They can make contacts and send messages in your name with this information.

Setting up a secure PIN Code on your SIM is an essential security measure you can implement to avoid SIM cloning.

• SIM Card Swapping 

A hacker will first contact your phone provider to conduct a SIM card swap hack. They will pose as you and request a replacement SIM card. Then, they can link your phone number to their device.

To protect yourself against SIM card swaps, make it hard for hackers to find information about you. Try to lock down essential details available only by limiting public information being shared on other sites.

• SIM Card Hijacking

This is another method cybercriminals use to impersonate you. They call your cell phone provider and persuade them to alter the SIM card. 

Hackers transfer the information from your SIM card to another card, gaining access to your text messages. Fraudsters can reset passwords via text message, increasing your bank account risk. 

Always use passwords that are strong and uniquely generated. Avoid using simple passwords or the same password for multiple accounts. You can also set the two-factor authentication to secure better your credentials and the resources you can access.

Conclusion

A SIM card is a vital component with unique information differentiating your phone from other devices. It enables authentication with the network provider and conveniently stores essential data, including personal information. 

However, due to limited storage capacity, it is advisable to utilize an SD card for storing large files like videos and pictures.

To keep your SIM card secure, it's important to take steps to prevent hacking attempts. Using strong passwords and PINs is highly recommended, reinforcing the overall protection of your mobile device and its sensitive data.