Exactly What Information Does My SIM Card Contain About Me?

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Exactly What Information Does My SIM Card Contain About Me?
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Exactly What Information Does My SIM Card Contain About Me?

The SIM card is a memory circuit in your cell phone that carries necessary information back and forth to your network, and it also contains some of your personal data. While the information that your service provider needs is not changeable or removable, you can control some aspects of your personal information. You need to know what information is non-negotiable, what information is negotiable, and how to protect your information in case of prying eyes, theft, or loss of your cell phone and SIM card.

Overview of Cellular Systems and SIM Cards

A SIM (Subscriber Identification Module or Subscriber Identity Module) is a smart card for mobile telephones and tablets. It is a thin card with electronic circuits that is easily removed from a mobile device and placed into another. Forensic detectives and hackers have software programs that can access your information remotely, and your cellular carrier does maintain offsite records of your information and activities. The cellular carriers maintain these records at internal or offsite servers, which in theory can be hacked and your information stolen. Also, anyone can buy a SIM card reader and obtain at least some of your personal information if they’re able to get your SIM card in their hands. The SIM card contains a variety of information designed to allow the device to securely and reliably connect with networks and your contacts, but also has loopholes that make you vulnerable.

Security Systems on the SIM

First, the SIM card carries an authentication protocol in the form of algorithms and keys so that no unauthorized user can access your information remotely. Second, a cryptographic language guarantees your privacy by encrypting your data, decoding it when appropriate, and confirming when the information reaches its destination. Third, the SIM card carries a fraud protocol that prevents alteration of data or receiving services that have not been paid for.

Cellular Systems and Carriers

The most widely used system worldwide is the Global System for Mobile Communications (GSM), but others include CDMA, D-AMPS, and PDC. These systems are very complex communication protocols governed by agencies and operating procedures.

The GSM System

This system affects you and your SIM card in two ways. One is the infrastructure of GSM and the other is the end user. The end user is you and every part of the system that affects you, called the Mobile Station (MS). The MS divides further into subparts, the Mobile Equipment (ME), which is your phone, and your SIM card.

A SIM Card Does Not Contain

Your SIM card is protected by various protocols, but protocols can be penetrated. Luckily, your SIM card does not contain highly personal and sensitive information like pictures and videos. It does not store your home address, your bank account number, your doctor’s name, or other details unless you specifically write those details in a text (SMS) message or specify those details in your contact lists.

Cellular carriers only archive SMS messages for a brief period on their network servers. For example, most major providers in the United States store the messages in the archives from about 48 hours to two weeks. The exceptions are if you: subscribe to a service that specifically offers text archiving, are subject to a court order for message archiving, work for a government agency, or possibly, live in a country known for spying on its citizens.

The caveat to this is that while the carrier deletes messages in order to make space on its servers, you do the same thing on your mobile device, too. However, deleted messages only mean that you cannot see them anymore; they are still present on the SIM card until overwritten by new data.

The SIM Card Does Contain

Along with the text messages, the SIM card holds your phone contacts with the related information like names and numbers, and history of calls including dates and times. This is why law enforcement seeks to gain entry to SIM cards in order to connect criminals to their associates. The SIM card also contains several pieces of information that relate to the security protocols, the network carrier, your Personal Identification Number (PIN), an unblocking code, and the services you use, like applications. Another very important piece of data is the last location of the phone, which is often useful in locating missing people.

Following is a chart with a list of information stored on the SIM card, its abbreviation if there is one, and a brief description.

SIM Information



Advice of Charge


Governs payments and receipts of your services.

Authentication Key


Recognizes you as the authorized user.

International Mobile Subscriber Identity


Allows the network to identify the device.

Mobile Country Code


Identifies the country of origin by a two- or three-digit code.

Mobile Subscriber Identification Number


Ten-digit code that is the link between you and your cellular carrier.

Mobile Subscriber International ISDN Number


A code to decipher who you made calls to. You can change this number.

Local Area Identity


As your data travels between communication points, the SIM stores codes about the local networks.

Personal Identification Number


The code you use to lock and unlock the phone.

Service Dialing Number


The numbers used to access your services like voicemail.

Service Provider Name


The name of your cellular carrier.

Short Message Service Center


The service center(s) where your text messages are processed.

Unblocking Code


If you enter the wrong PIN too many times, the phone locks. The PUK, retrieved from the carrier, unlocks the phone.

Integrated Circuit Card ID


The card’s unique serial number.

Value Added Services


The services and applications that you use or pay for, like call waiting or forwarding.

These information sets were developed over the years by different governing agencies, which developed protocols both in the United States and abroad. The individual codes feature varying parameters of a technical nature and are subject to change as communication technology evolves. For instance, the International Mobile Subscriber Identity (IMSI) is the code that permits the cellular carrier to recognize the device. This code contains digits that represent the country, the carrier, and the subscriber. The code varies between 10 and 15 digits, and that may change over time.

Controlling the Information on the SIM Card

While most of the codes on the SIM card must be stored on the card in order for you to use the phone, you can control some information. By default, your text messages will disappear after a short period from the carrier’s servers, but remain on the card until overwritten by new data. You can however, with a device called a SIM reader, view, backup, and physically delete information from the SIM card.

To do this, obtain a SIM reader. It is a small USB device that plugs into your computer, and comes with software that interfaces with your SIM card. Install the software and insert the SIM card into the reader. From there, you can perform a variety of tasks, which include downloading your contacts and text messages onto your computer. You can even sync your cell phone information with other software on your computer like address books. If your SIM reader also has a write function, you can even transfer information from one SIM card to the other.

The SIM card readers are helpful to you, but are also an avenue for prying eyes to infringe on your privacy rights and steal your identity. One way you can protect your SIM card in case of loss or theft is to contact your service provider and ask them to lock the SIM card. This simple step prevents anyone from reading your SIM card or using it in another phone. Keep in mind that this step does not lock your phone. You must do that in addition for extra safety. Also keep in mind that your cellular carrier may provide a remote wiping service, whereby as soon as you call and give the appropriate authentication, they will delete the information you request.

Buying on eBay

SIM cards and SIM card readers are available on eBay. To find SIM cards and SIM card readers, enter the terms in the search box. Alternatively, use the Electronics portal and choose Cell Phones. Choose SIM Cards or SIM Card Readers. Remember to choose a SIM card reader/writer if you want both capabilities. Both categories offer refinement selections according to network carrier. Also be clear on whether the SIM card is new, refurbished, or new.

Since the SIM card does contain electronic circuits, they are vulnerable to static electricity, which can irreparably harm the card. New SIM cards should be in the original packaging, which should protect them from static electricity. Used or refurbished SIM cards should be packaged in an anti-static bag. Ask sellers if this is their normal practice. Also, look for sellers who provide a reasonable return policy if the SIM is damaged. Instructions on how to use the SIM would be helpful to you, as well as continued availability and communication should you have difficulty installing and activating your SIM card.


SIM card information is not of great interest to hackers and criminals, as they are mainly concerned with breaking into banks and credit card companies in pursuit of the almighty dollar. However, identity theft is on the rise and oftentimes people overstep their boundaries and trample on your privacy rights by trying to gain information from your SIM card. SIM card readers make this practice easier. The information on your SIM card of interest to these people is primarily your text messages and your phone book. You can control this information for your own purposes by downloading and/or deleting the information and by locking down your SIM card with a call to your service provider. If your provider does not provide such a service, you may want to switch to a carrier who does.

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