What Is Stored on a SIM Card? Everything You Need to Know
A SIM card stores subscriber identity, network information, & security credentials, while some physical SIMs also hold limited contacts and SMS. Photos, apps, passwords, and most personal data stay on your phone or in the cloud. Understand SIM security, eSIMs, and what happens when you switch cards.
A SIM card primarily stores subscriber identification, network information, and security credentials. Some physical SIM cards can also hold a limited number of contacts and text messages. However, photos, apps, and most personal data are stored on your phone or in the cloud.
A SIM (Subscriber Identity Module) helps your mobile carrier recognize and authenticate your subscription.
This guide explains "what is stored on a SIM card", how SIM storage differs from phone storage, and what happens to your information when you remove or replace a SIM.
Quick Answer: What Is Stored on a SIM Card?
A SIM card typically contains:
- IMSI: Identifies your mobile subscription to the network.
- ICCID: A unique identification number for the SIM or eSIM profile.
- Authentication information: Secure credentials used to verify your subscription.
- Carrier and network information: Helps your phone connect to supported networks.
- PIN-related security information: Protects your SIM against unauthorized use.
- Contacts and SMS: Some physical SIMs can store limited contact entries and traditional text messages.
So, "what does a SIM card do"? It securely identifies and authenticates your mobile subscription, allowing your phone to use supported cellular services.
Important: Your photos, videos, apps, passwords, and browsing history are not normally stored on the SIM.
What Information Is Stored on a SIM Card?
If you're wondering "what is on a SIM card", here's a closer look at the identifiers and security information that help it work.
IMSI
The International Mobile Subscriber Identity (IMSI) identifies your mobile subscription. It contains up to 15 digits, including a mobile country code, a mobile network code, and a subscriber identification number.
Your carrier uses this information to recognize your subscription when connecting to a mobile network.
ICCID
The Integrated Circuit Card Identifier (ICCID) identifies a physical SIM or an individual eSIM profile.
It commonly contains 19 or 20 digits, typically begins with 89, and may be printed on the physical SIM or its packaging.
The distinction is simple: IMSI identifies the mobile subscription, while ICCID identifies the SIM or profile associated with it.
Read more: Your SIM also plays a role in how your phone connects to mobile networks. Before travelling abroad, read What Is GSM and Why Does It Matter When Traveling Abroad? to understand network compatibility and why it matters when using your phone in another country.
Authentication Key
A SIM securely holds authentication credentials used to prove that your subscription is legitimate.
When your phone connects to the network, the SIM participates in a security check without transmitting its secret authentication key.
So, "what does a SIM card do" during authentication? It helps the carrier verify that your subscription is authorized to access the network.
These protected credentials cannot normally be viewed or exported through your phone's settings.
Carrier and Network Information
SIMs contain operator identification and network-related information that helps your phone register with supported mobile networks.
These settings are generally managed by the carrier rather than edited manually.
PIN and PUK Information
A SIM PIN provides an extra layer of security. When enabled, it must be entered before the SIM can be used after certain events, such as restarting the phone.
Entering an incorrect PIN too many times, commonly three attempts, can block the SIM. You'll then need a PUK (PIN Unblocking Key) to restore access.
The PUK is normally provided through your carrier or SIM documentation. You shouldn't attempt to guess it because repeated incorrect entries can permanently block the SIM.
Remember: Your SIM PIN is different from your phone's screen-lock passcode.
Phone Number
Your mobile number is associated with your subscription in your carrier's systems.
Some SIMs contain a phone-number field, but it may be empty or outdated. The number doesn't have to be stored there for your phone service to work.
Your "SIM card holder details", including your registered name and identification documents, are generally kept in your carrier's customer records rather than directly on the SIM.
Contacts and SMS
Some physical SIMs can store a limited number of basic contacts and traditional SMS messages.
This was more useful on older phones with little internal storage. Modern smartphones generally rely on device storage and account-based synchronization instead.
What Is NOT Stored on a SIM Card?
Knowing "whats on the SIM card" also helps clarify which information is stored elsewhere.
- Photos and videos: Saved on your phone, memory card, or cloud storage.
- Apps and app data: Stored on your device or associated online accounts.
- Passwords: Usually saved in secure device storage, password managers, browsers, or apps.
- Browsing history: Maintained by your browser and sometimes synchronized with your account.
- Most call history: Stored on the device or associated service, although some SIMs can retain limited dialed-number information.
- WhatsApp, iMessage, and other app messages: Managed through their respective apps and backup systems.
- Emails and documents: Kept in device storage, apps, or cloud services.
These items don't normally move with your physical SIM when you insert it into another phone.
SIM Card vs. Phone Storage vs. Cloud Storage
The table below shows "what is on a SIM card" compared with phone storage and cloud accounts in a typical modern setup.
Storage behavior varies by device, operating system, carrier, and application. A phone may also display SIM identifiers without storing the protected credentials itself.
How Much Data Can a SIM Card Store?
SIM cards have very little storage compared with smartphones.
Older SIM cards are commonly described as having capacities ranging from about 8 KB to 256 KB, although this is not a universal limit for modern SIMs or embedded SIM hardware.
Their storage is designed primarily for subscription information and security functions, not large personal files.
So, "does SIM card store data"? Yes, but it doesn't provide general-purpose storage like your phone's internal memory.
And "what does a SIM card store" within that limited space? Mainly network-related records and, on supported physical SIMs, a small number of contacts or messages.
What Does a SIM Card Look Like?
A physical SIM is a small plastic card with metallic contacts on one side and a cut corner to help it fit correctly into a compatible slot.
SIM cards come in four standard physical sizes:
- Full-size SIM (1FF): Approximately 85.6 × 54 mm, roughly credit-card sized.
- Mini-SIM (2FF): 25 × 15 mm, found in older mobile phones.
- Micro-SIM (3FF): 15 × 12 mm, common in earlier smartphones.
- Nano-SIM (4FF): 12.3 × 8.8 mm, used in most current phones that support removable SIM cards.
An eSIM doesn't have a removable plastic card because its SIM functionality is provided through hardware built into the device.
What Happens to Your Data When You Remove a SIM Card?
Removing a SIM does not delete your personal files or apps. Your phone's stored information stays intact.
What changes is access to the mobile subscription associated with that SIM.
- Cellular connection: Calls, traditional SMS, and mobile data through the removed SIM become unavailable unless another active SIM or eSIM provides service.
- SIM-only contacts: Contacts that were never imported or synchronized may no longer be accessible.
- SIM-stored SMS: Older messages stored directly on the SIM may become unavailable until you reinsert it.
Your phone can still connect to Wi-Fi, use supported internet-based services, and access cloud accounts.
Removing your SIM also doesn't automatically cancel your mobile plan.
Read more: Using a physical SIM and an eSIM on the same phone can make switching between your regular number and a travel data plan much easier. Here’s How Does a Dual SIM Phone Work? Explained Simply.
What Happens When You Switch to a New SIM Card?
Switching SIM cards usually changes which mobile subscription your phone uses. It does not reset the phone or erase its stored information.
What may change:
- Your carrier or cellular subscription.
- Your mobile number, depending on whether the existing number is transferred.
- Network-related settings and plan allowances.
What generally stays the same:
- Photos, videos, and documents.
- Installed apps and locally saved data.
- Browsing history and signed-in accounts.
- Contacts stored on the device or synchronized with an account.
If you're asking "what does a SIM card store" that might need transferring, check for contacts or messages saved exclusively to your old SIM.
If you're changing cards because yours stopped working, read our guide on Can a SIM Card Go Bad.
Are Contacts and Text Messages Stored on a SIM Card?
Contacts
Some physical SIMs support basic contact entries, usually names and phone numbers.
If you're wondering "does SIM card store data" such as your contacts, the answer depends on where they were originally saved.
On modern phones, contacts are commonly stored on the device or synchronized through iCloud, Google Contacts, or another account.
Before changing phones, check whether your contacts are already synchronized or need importing.
Text Messages
Some physical SIMs support storage for a limited number of traditional SMS messages.
Most modern smartphones store SMS conversations on the device, with backup or synchronization options depending on the messaging app and operating system.
Moving your SIM alone should not be treated as a method of transferring your full message history.
Does an eSIM Store the Same Information as a Physical SIM?
Yes. An eSIM performs the same core identification and authentication functions as a physical SIM, but its carrier profiles are managed digitally on compatible SIM hardware.
Instead of inserting a plastic card, you download a carrier profile onto the device.
Key differences include:
- Digital installation: Carrier profiles can be added through supported device settings, apps, or activation methods.
- Separate identifiers: Each eSIM profile has an ICCID, while the embedded SIM hardware has its own identifier, called an EID.
- Multiple profiles: Many devices can store several eSIM profiles, although the number that can be active at once varies.
- No removable card: Profiles are managed digitally rather than by physically swapping cards.
The EID identifies the embedded SIM hardware, while the ICCID identifies an individual profile.
If you're asking "does my phone have a SIM card", it may have a removable SIM, built-in eSIM capability, or both.
How to Check What Is Stored on Your SIM
Most phones allow you to view certain SIM identifiers and manage supported contacts. However, they don't provide a complete file browser for protected SIM information.
Does My Phone Have a SIM Card?
Your phone's SIM configuration depends on its model and country of purchase.
- Physical SIM: Check your phone's specifications for a removable SIM slot or tray.
- eSIM: Look for options to add or manage an eSIM under your mobile network settings.
- Both: Many dual-SIM phones support physical SIM and eSIM combinations.
On iPhone, go to Settings → Cellular or Mobile Service to view available lines.
On Google Pixel, check Settings → Network & internet → SIMs. Other Android manufacturers may use different menu names.
If you're checking "what does a SIM card look like", refer to the physical SIM sizes described earlier.
On iPhone
To import contacts saved on a compatible physical SIM:
- Insert the SIM containing your contacts.
- Open Settings → Apps → Contacts.
- Select Import SIM Contacts.
- Choose a destination account if prompted.
- Open Contacts to confirm the import.
On older iOS versions, Contacts may appear directly in Settings.
Apple confirms that iPhones can import supported SIM contacts but don't save new contacts to the physical SIM.
Read more: If you use an iPhone, you may have seen the “SOS Only” message when your phone loses its regular cellular connection. SOS Only on iPhone: How to Fix the Problem Step by Step walks through common causes and ways to troubleshoot the issue.
On Android
In the Google Contacts app:
- Insert the SIM containing your contacts.
- Open Contacts → Organize → Manage SIM.
- Select the contacts and destination Google Account.
- Tap Import.
The available menu labels may differ depending on your phone and Android version.
Using a SIM Reader
A compatible SIM reader may display certain accessible information, such as supported SIM contact records or older SMS entries.
However, protected authentication credentials aren't available through ordinary SIM readers.
Use reputable tools and avoid entering unknown PIN or PUK codes.
Can Someone Access Your Data From Your SIM Card?
A SIM contains sensitive subscriber information, but it isn't a complete copy of your phone.
Someone with your SIM generally cannot retrieve photos, installed apps, or cloud files from the SIM alone.
Your "SIM card holder details", including registration information, are generally maintained in your carrier's records rather than as a readable customer profile on the card.
However, an active SIM can still create security risks. Someone who gains control of your mobile number may be able to receive calls or SMS verification codes.
This can happen through physical SIM theft or SIM-swapping fraud, where an attacker persuades a carrier to transfer a number to another SIM.
To protect your mobile account:
- Enable a SIM PIN: Helps prevent unauthorized use of a physical SIM in another phone.
- Secure your carrier account: Use a strong password and any available account PIN or number-transfer protection.
- Avoid relying only on SMS verification: Use an authenticator app or security key where supported.
- Report a missing SIM promptly: Ask your carrier to suspend the affected service and provide a replacement.
Protecting your SIM matters even though "whats on the SIM card" is much more limited than the personal information stored on your phone.
Read more: SIM security is only one part of keeping your conversations private. If you use iMessage, How to Encrypt iMessage and Keep Your Messages More Secure explains how message encryption works and what you can do to protect your chats.
Stay Connected With an eSIM When You Travel
An eSIM for international travel lets you add a mobile data plan without physically replacing your regular SIM, provided your phone is unlocked and eSIM-compatible.
This is particularly useful when travelling because you can keep your home line available while using a separate data plan for navigation, translation, transport, bookings, and messaging.
Jetpac international eSIM keeps travelers connected across 200+ destinations with one reusable eSIM profile. It supports automatic switching between available partner networks for a stronger connection and unlimited hotspot sharing without separate tethering restrictions.
Even after regular data runs out, travelers can continue accessing essential apps like WhatsApp, Google Maps, Uber, and Grab on eligible plans. Jetpac also offers in-app voice calling to supported phone numbers, with voice packs starting at $1.99.
When choosing the best eSIM for international travel, check destination coverage, data allowances, activation conditions, and hotspot support.
The best eSIM for international travel is the one that meets your travel needs and provides suitable coverage, rather than simply the lowest advertised price.
Read more: You can often keep your regular number active while using an eSIM for mobile data on a compatible phone. Can I use eSIM with a Physical SIM Card Together? explains how the two work together and what to check before setting them up.
FAQs
Can a SIM Card Store Photos or Videos?
No. Photos and videos are stored on your phone, memory card, or in cloud storage rather than on the SIM.
Does a SIM Card Store Your Browsing History?
No. Browsing history is maintained by your browser or device and may synchronize with an online account.
Does Removing a SIM Card Delete Anything From Your Phone?
No. Your personal files, installed apps, and locally saved information remain on the phone. Removing the SIM affects the mobile subscription and access to information saved only on that card.
What Happens to Your Data When You Switch SIM Cards?
Your phone's stored data generally remains unchanged. Your mobile service may change, and the number you use depends on whether your existing number is transferred.
How Can I Transfer Contacts From a SIM Card to a New Phone?
Insert the SIM into a compatible phone and use its contact-import feature.
On iPhone, use Settings → Apps → Contacts → Import SIM Contacts. On Android, use the relevant import option in Contacts.
You can also transfer supported contacts through Google Contacts, iCloud, or a compatible contact file.
Does an eSIM Store the Same Information as a Physical SIM?
An eSIM stores the same general types of subscriber and network credentials through a digital profile. It doesn't act as storage for personal files, photos, or apps.
Can a SIM Card Be Used to Recover Deleted Messages?
Not reliably. A SIM isn't a general backup of your text conversations. Modern messages are usually stored on the phone or through app-specific systems. For recovery, check available device or account backups. Specialist recovery of older SIM-stored messages is not guaranteed.
Disclaimer
This article is for educational and general informational purposes only. Information is based on publicly available technical documentation and product information as of October 2026. SIM and eSIM capabilities, device settings, mobile carrier requirements, and service features may vary or change without notice. Always confirm important details with your device manufacturer or service provider. Jetpac is not responsible for inaccuracies, subsequent changes, or losses arising from reliance on this information.
Get connected as soon as you land with a Jetpac travel eSIM.
