What is stored on a SIM card? Stored and not stored information

Does the SIM card store data?

Yes, SIM cards do store some data related to your contacts and network data, which lets you connect to the internet, make phone calls, or send SMS messages. However, SIMs do not hold much of your personal information, with the physical cards only storing your contacts, phone number, and SMS messages.

Over the course of the physical SIM card’s evolution — and as counterintuitive as it might sound — the smaller it got, the more storage it had. The original SIM, which, again, was the size of a modern credit card, was capable of storing up to 32 KB of data, or enough for five SMS messages and 20 contacts. The current generation of SIM cards, the nano-SIM, has 128 KB of memory capacity, or enough to save up to 250 contacts.

Beyond personal information, all SIMs — the SIM, mini-SIM, micro-SIM, or nano-SIM — have mobile network information that helps your carrier identify you as a user, and allow you to call, text, or access the internet.

Embedded SIMs (eSIMs) store similar records to allow you to either call, text, or browse the web, or if you’ve got a travel eSIM like Saily, tap into the data provided by your plan.

Find out more about the key differences between a physical SIM card and an eSIM.

What is stored on a SIM card?

Each SIM card’s storage holds information related to you personally, like your contacts, phone number, and text messages, and your network carrier, like authentication keys or other identification details. Here’s a breakdown of some of the main things that a SIM card holds:

• Carrier settings and information. Each SIM card stores carrier-specific information about the provider’s name, network settings, and cellular plan subscription.

• The international mobile subscriber identity (IMSI). The IMSI is a unique number assigned to your SIM, allowing phone networks to identify users and assign them a mobile carrier.

• The integrated circuit card identifier (ICCID). Acting like a SIM’s fingerprint, the ICCID is used by networks to recognize a user’s SIM card. The first six to eight digits of the ICCID are issuer identification numbers (IIN), a number that identifies the card’s issuer, usually a mobile network. The rest of the ICCID consists of an individual account identification and a check digit.

• The location area identity (LAI). LAI is the code that helps phone networks identify the location of your device, with each public land mobile network (PLMN) area having a unique identifier that is sent to your Apple or Android phone and stored in a SIM to locate the nearest cell tower in case of a call or a text message.

• Authentication key (Ki). The Ki is used to verify a user’s identity on a mobile network in a secure and encrypted manner.

• Your subscription information. Mobile carriers know users’ call minutes, the number of SMS messages, and network data usage via the information that a SIM provides to them.

• Your personal identification number (PIN) and personal unblocking key (PUK). Both codes are stored in your SIM, with the PIN unlocking a SIM card after you’ve restarted your phone, for example. The PUK is used when you’ve incorrectly entered the PIN three times in a row to unblock the SIM.

• Your phone number. Even if today’s SIM cards can store more data, the one thing that has stayed constant throughout the evolution of the SIM — even including the progression into an eSIM — is that each SIM card holds your phone number to identify when you make or receive calls.

• Your contacts. While modern smartphones can and mostly do archive your contacts in a cloud storage service or locally, SIM cards also store the list of your contacts.

• Your SMS messages. In addition to your contact list, SIMs will store your text messages locally if they are not sent via third-party apps or iMessage, which is Apple’s instant messaging service across its operating systems.

These are the main things that are stored on a SIM, enabling the basic functions of a mobile phone: calling, texting, and surfing the web.

What other information and data do SIM cards hold?

While they’re essential for mobile connectivity, SIM cards don’t act as additional phone storage. They don’t store your photos, apps, or other files. The data that they hold is limited to what’s necessary to keep your phone connected to the network. Why? Simply because the storage of a SIM is very limited. The standard SIM capacity ranges from 8 KB to 256 KB, which we can agree is not a lot. So, instead, all your personal files stay in your phone’s internal memory or the cloud.

That being said, it’s important to remember that SIM cards can “go bad” and stop working over time. If that happens, you might lose this data saved directly on the card. It’s always smart to back up your contacts just in case.

Are contacts stored on the SIM card?

SIM cards can store contacts, but the space is pretty limited compared to other options. As mentioned before, the size of SIM cards ranges between 8 KB and 256 KB, which holds about 250 contacts in total. These contacts are stored in a simple format, typically including only the names and phone numbers.

Back in the day, saving contacts to a SIM card was a handy way to transfer them between phones. You’d just pop the SIM into a new device, and your contact list would automatically transfer, too.

Because technology has come a long way since then, most people now prefer to store their phone numbers in cloud services like Google Contacts or iCloud. Cloud technology makes it easy to access contacts across multiple phones. Plus, if your SIM gets damaged or lost, you won’t lose your contacts.

If you still save contacts to your SIM, backing them up is a good idea. Modern smartphones offer much more storage and flexibility than a SIM card ever could, and they typically default to using cloud or internal storage anyway. This way, you’ll be sure all your contacts will be in one place.

Are text messages stored on the SIM card?

Some SIM cards can store text messages, but as mentioned earlier, the capacity is limited and varies depending on the card. This feature was more useful for older cell phones or users who preferred saving specific messages directly to the SIM.

Today, however, saving SMS to SIM cards is mostly irrelevant. In newer mobile devices, messages are typically saved to the phone’s internal memory or, in some cases, backed up to the cloud by default.

Are pictures stored on the SIM card?

SIM cards don’t store pictures. Their storage capacity is simply far too small to fit photo files. This very limited space is reserved for essentials like your phone number, contacts, and basic network data.

In the past, people might have thought of SIM cards as general storage, but today’s smartphones rely on internal memory, SD cards, or cloud storage for handling media files like photos and videos. 

If you're switching SIM cards or upgrading your phone, make sure to back up your photos first. You can sync them to the cloud or transfer them to a computer or external storage to avoid losing them. Otherwise, you risk losing them during the transition.

How much data storage does a SIM card have?

The amount of data that can be stored on a SIM depends on the SIM card that you actually have. The earliest SIM, which was quite a bit larger than the current-generation physical cards, had a capacity for up to 4 KB of data. In practical terms, this meant that the first-generation SIMs held up to five SMS messages and 20 contacts.

Then, the mini-SIM introduced up to 64 KB of storage, followed by the macro-SIM, which had between 64 KB and 128 KB of storage. The nano-SIM, the latest iteration of the physical SIM card, offers between 128 KB and 256 KB of storage, storing up to 250 contacts and 50 text messages.

The evolution of the SIM did not end there, and in 2016, Samsung introduced the first device with an embedded subscriber identity module (eSIM). The eSIM, soldered onto the device’s motherboard, has a storage capacity of up to 512 KB in consumer devices, like phones or smartwatches. 

Some have considered that with the advent of the eSIM, regular SIM cards would be dead. While that is yet to happen, eSIMs have gained in popularity, and some phone manufacturers, like Apple, opted to issue the newest iPhone 17s without a physical SIM card tray in select countries. For example, the iPhone Air is eSIM only worldwide. The first eSIM-only smartphone was the Motorola Razr, which Motorola released in 2020.

If you’re wondering where your contacts are stored on an eSIM, on the iPhone, for example, they are saved on your iCloud account. Similarly, on the Google Pixel, contacts are stored in the cloud as well and will be synced via your Google account.

What is not stored on a SIM card?

While physical SIM cards have some storage capacity, they are designed to only contain various pieces of information that make sure you can make calls, text your friends or family, and connect to mobile networks to access the internet. Beyond that, everything goes onto the phone’s internal storage, the size of which depends on the exact model of your device. SIMs do not store:

• Call history.

• Multimedia like photos, videos, or music.

• Apps.

• Browsing history.

• Downloads.

With SIMs having limited space, saving any of this data on the card could take up the whole storage capacity of a SIM, making it an impractical solution. Thus, phones store pictures, videos, music, apps, files, and history either internally or in a cloud service, like Apple’s iCloud.

How to check information about your SIM on an iPhone and Android

While not all the information is easily visible, both iPhones and Android phones allow you to check essential details tied to your SIM, like your phone number and network info. If you’re curious to know more about your SIM card, you can find this information in just a few taps.

How to check information about your SIM on an iPhone

If you’re using an iPhone, here’s how to check what information is stored on your SIM card:

1. Open “Settings” on your iPhone.

   

2. Scroll down to find a tab called “General.”

   

3. Go to “About.” Here, you’ll find your SIM card’s ICCID and information about your network provider. If you tap “Network provider,” you’ll find your IMS status, which is the state of your device's connection to the network.

   

4. To find even more information about your SIM, return to the main screen of the “Settings” app. Scroll down and tap on “Cellular” (or “Mobile service” in some cases) > “SIMs.” 

   

5. Choose your SIM card. 

   

From there, you can explore additional details about your SIM, like your phone number and network selection, and adjust settings like data roaming or switch between 5G and 4G. 

How to check information about your SIM on an Android

For Android users, checking information about your SIM card is just as easy:

1. Open the settings on your Android device.

   

2. Scroll down and tap on “About phone” > “Status.”

   

3. Tap on “SIM status.” 

   

Here, you’ll see essential information like your network, roaming status, and phone number tied to your SIM card.

Does removing a SIM card delete data stored on it?

Removing a physical SIM card from a phone or another device does not remove any data. The SIM maintains the data stored on it, including your contacts and text messages — or if you have a newer smartphone, your contacts are already synced to the cloud.

If you’re using an eSIM, disabling it will not delete the data stored on it. However, if you manually delete an eSIM profile from your phone, the data will disappear. Then again, most recently released phones store information either locally or in the cloud, so a deleted eSIM will not result in any loss of data.

What is stored on a SIM card: Key takeaways

SIM cards store critical network information and some personal information, like a user’s phone number. While on older phone models, and when cloud technology was not as advanced, contacts were also kept on a SIM card. Today, the phone numbers of your contacts are either stored in the phone’s memory or in the cloud.

Furthermore, any type of multimedia, whether videos, photos, or music, as well as apps, browsing histories, or downloads, is kept on the phone or, again, in the cloud.

The same can be said about eSIMs. eSIMs, the technology of which is almost a decade old, stores minimal personal data and only what’s essential to connect the phone to a mobile network, even if you’re using a travel eSIM like Saily.

Saily is an eSIM service that, in addition to providing phone numbers or mobile data, allows users to purchase lounge access or even fast-track services once they download the eSIM app.