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

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Velina Nenova
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Velina Nenova

Updated · Aug 02, 2023

Velina Nenova
Social Media and Digital Marketing Expert | Joined March 2022 | LinkedIn
Velina Nenova

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Florence Desiata
Joined June 2023 | LinkedIn
Florence Desiata

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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.

Key Takeaways


A SIM card stores your phone number, contacts, text messages, authentication key, IMSI, MCC, MSIN, etc.


The storage capacity of a SIM card typically ranges from 8KB to 512KB. It can hold up to 250 contacts and some messages.


A SIM card lets your phone connect to your carrier's network. It lets you make calls, send texts, and use mobile internet data.


There are five main types of SIM cards based on size: full size, mini, micro, nano, and eSIM.

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:

Data Stored on a SIM card 


Advice of Charge (AoC)

Authentication Key (Ki)

  • Unique for each SIM
  • It consists of a 128-bit value used to authenticate the SIM card on the network.

International Mobile Subscriber Identity (IMSI)

  • The number identifying your SIM card within your mobile network operator.

Mobile Country Code (MCC)

  • Represents the first three digits of the IMSI number. Identify GSM networks worldwide.

Mobile Subscriber Identification Number (MSIN)

  • Identifies a subscriber from a mobile network
  • works as a link between the network and the user.

Mobile Station Integrated Services Digital Network (MSISDN)

  • The phone number you need to dial to establish communication
  • can be changed if the subscriber requires it.

Local Area Identity (LAI)

  • This identifier consists of the mobile country code (MCC), 
  • the mobile network code (MNC)
  • the location area code (LAC).

Personal Identification Number (PIN)

  • This code is used to lock and unlock the mobile device.
  • It can be changed if necessary
  • Usually made up of four digits and can also be disabled.

Service Dialing Number (SDN)

  • Numbers provided by the mobile operator
  • Users can access services

Service Provider Name (SPN)

  • The name of your mobile operator.

Short Message Service Center (SMSC)

  • The service center stores, processes, and delivers your text messages 

Unblocking Code (PUK)

  • Code is used when the user enters the wrong PIN. The phone locks and asks for the PUK code provided by the mobile operator.

Integrated Circuit Card ID (ICCID)

  • A number that identifies a SIM card
  • Consists of an 18 – 22 digits code
  • Unique for each SIM card worldwide. 

Value-Added Services (VAS)

  • Refers to additional services the customer uses and pays for.

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

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.

In a nutshell: 

Since their 1991 debut, SIM cards have evolved from credit card-sized to minuscule nano versions. 

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.


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

Step 1. Navigate to Settings and select About Phone.

Navigate to Settings and select About Phone

Step 2. Search About phone and then select Status.

Search About phone and then select Status

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

Click SIM status


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.

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.

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.

Pro Tip: Aside from setting up a secure password, you can also set up a three-factor authentication and multi-factor authentication to protect your sim card.

  • 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.

Pro Tip: To learn more about protecting yourself from identity theft, visit Techjury articles on identity security and personally identifiable information.


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.


What is not stored on a SIM card?

SIM cards do not store photos and videos as they have limited storage capacity, typically only up to 512 KB, which is insufficient for larger file sizes.

Will removing the SIM card delete everything?

No, when you remove your SIM card from your phone, you lose access to all the information stored on it, including your contacts and other essential details. However, the card removal does not affect photos, apps, and other documents not stored on the SIM.

What happens if you take your SIM card out and put it in another phone?

The only information that will be transferred is your phone number, text messages, and contacts. Your old phone will retain the remainder of your data, including photographs, videos, and other files.

Can I just put my old SIM card in my new phone?

Yes, you can. You can transfer SIM cards between devices if your new phone is compatible with the SIM card type and the same carrier network.

What information needs to be recovered when switching SIM cards?

You must recover all your SIM card data, including your user identity, location and phone number, network authorization data, personal security keys, contact lists, and stored text messages.


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