The Mobile Subscriber Identity Number, or IMSI, is a critical parameter for the operation of any cell phone. This unique code is stored on the SIM card and allows cell towers to uniquely identify the device on the global network. Regular users rarely have to look at this number, but for information security specialists, mobile application developers, or when solving complex communication problems, knowledge of IMSI becomes mandatory.
Unlike the more well-known IMEI number, which is tied to the smartphone hardware itself, IMSI belongs specifically to your SIM card. When you replace your SIM card, this code will change, even if you keep the same phone. GSM and LTE mobile communication standards use this identifier to route calls and check the subscriber's access rights to the operator's network. Understanding the difference between these concepts helps to avoid confusion when diagnosing a network.
There are several proven ways to obtain this information on devices running an operating system Android. Some methods do not require root access and work on most modern models, while others may require connecting to a computer or using special diagnostic utilities. In this article we will analyze in detail each of the available options, from the simplest to the advanced.
Using the engineering menu and USSD requests
The fastest way to access technical information about a SIM card is to use special codes entered through the “Phone” application. Smartphone manufacturers often implement hidden menus intended for service engineers, where the average user does not have direct access through standard settings. Entering a combination of characters can open an interface with detailed data about the radio module.
However, there is no universal command for all devices. On smartphones Samsung, Xiaomi or Meizu the set of codes may be radically different. The combination ##4636##is often used, which opens the testing menu. If this code doesn't work, it's worth trying options specific to your processor or shell. For example, codes of the form ##3646633##.
⚠️ are popular on MediaTek chips. Attention: Be extremely careful when changing settings in the engineering menu. Accidentally changing the preferred network type or resetting the radio module parameters can lead to a complete loss of communication and require reflashing the device.
If the engineering menu does not display IMSI directly, you can try using USSD requests specific to your telecom operator. Some mobile operators provide a service for checking the status of a SIM card, where the response message may contain part of the identifier or the full number. This method is less reliable, as it depends on the policy of a particular service provider.
If standard codes do not work, try entering them in dialing mode without pressing the call button - the menu often opens automatically after entering the last character.
Viewing information through system settings
Starting with certain versions of the operating system Android, Google's privacy policies have become stricter. Previously, any user could go to the “About phone” section and see the IMSI in the public domain. Now this information is often hidden from the eyes of the average user to prevent tracking and fraud. However, on some shells the path to the data is still open.
Try the following route in your device settings: go to Settings → About phone → SIM card status. In some cases, especially on older versions of Android or custom firmware, a field IMSI will be displayed next to the phone number and network status. If instead of numbers you see dashes or the inscription “Unknown,” it means that the system is blocking access to this data at the software interface level.
On devices with pure Android or similar shells, the path may look different. Sometimes you need to go to Settings → System → Advanced → About phone. Here you should look for a section dedicated to network status. The absence of an explicit field for IMSI does not mean that the data is lost - it is simply hidden from the standard display for security purposes.
Starting with Android 10, access to caller IDs for third-party applications and sometimes for system settings themselves has been significantly limited for security purposes privacy.
Use of third-party diagnostic utilities
When the built-in system tools do not produce results, specialized applications from the store come to the rescue. Google Play. There are many utilities that position themselves as tools for checking the network and diagnosing equipment. They request special permissions to read the phone's state, which allows them to extract hidden information through system APIs.
Popular applications such as Phone Info SAM, Device Info HW or TestMare capable of displaying detailed information about the SIM card. After installing such software, you must grant it all requested permissions, including access to telephony. The app interface usually has a “SIM” or “Network” tab, where the required code is displayed.
- 📱 Phone Info SAM: great for Samsung devices, shows detailed information about the firmware and network.
- 📡 Network Cell Info Lite: specializes in monitoring towers, but also displays SIM card data.
- 🔧 AIDA64: a powerful utility for complete hardware diagnostics, including the communication module.
It is worth considering that on modern versions of Android, even these applications may not have access to the full IMSI due to system limitations. In this case, they may only display part of the number or a placeholder. This is normal system behavior designed to protect the user from leakage of personal data.
Using the ADB command line
For advanced users with access to a computer, the most reliable method is to use the debug bridge Android Debug Bridge (ADB). This tool allows you to send commands directly to the system, bypassing the GUI and many user-level restrictions. To work, you will need to enable USB debugging in the developer menu.
After connecting the smartphone to the PC and installing the drivers, open the command line or terminal. Enter the command to enter the device shell: adb shell. Next, you can use specific requests to the telephony service. One of the working commands is a request to the service iphonesubinfo, which returns a subscription to communication services.
adb shell service call iphonesubinfo 1The result of the command will return a string in Unicode format containing IMSI. You will need to parse the resulting sequence of characters, removing unnecessary overhead. This method almost always works, even if the phone settings are locked, since it accesses low-level system services.
⚠️ Attention: To use ADB, you must activate developer mode. Do not connect your phone to unfamiliar computers in this mode to avoid unauthorized access to your data.
Obtaining root access and direct access to files
Having superuser rights (Root) removes almost all operating system restrictions. If your device is rooted, you can access the file system where the modem and SIM card configuration data is stored. This is the deepest level of interaction with the smartphone hardware.
Using file managers with Root support, such as Root Explorer or Solid Explorer, you can go to system directories. Often network information is cached in radio configuration files. However, directly searching for IMSI in text form in files may not be successful, since the data is often stored in binary format or encrypted.
A more effective method if you have Root is to use terminal emulators directly on the phone. You can run the command su to obtain superuser rights, and then run the same request to the service iphonesubinfothat was used in ADB, but locally. This guarantees that you will receive a response without the need to connect to a computer.
Risks of obtaining root access
The rooting process will void the warranty on the device. In addition, incorrect actions with system files can lead to a “bricked” phone, which will be extremely difficult or impossible to restore.
Table of differences between IMSI and IMEI
A common mistake made by users is to confuse the concepts of IMSI and IMEI. Although both numbers are used for online identification, their purpose and storage location are fundamentally different. Understanding this difference is important to correctly diagnose communication problems or when a device is blocked.
The table below clearly shows the key differences between these identifiers. This will help you determine exactly what code you need to solve your problem.
| Characteristics | IMSI | IMEI |
|---|---|---|
| Storage location | SIM card | Phone memory (modem) |
| When changing SIM cards | Changes | Remains the same |
| Number length | 15 digits | 15 digits |
| Main purpose | Subscriber identification | Device identification |
| Who issues | Mobile operator | Phone manufacturer |
If you have lost your phone, you need to block it by IMEI, since this number is tied to the device. If the problem is the registration of the SIM card on the network or operator authentication errors, then diagnostics should be carried out by checking IMSI. Telecom operators see both numbers when you connect your device to the tower.
Questions and answers
Is it possible to find out the IMSI of another person by phone number?
No, this is technically impossible for an ordinary user. IMSI is transmitted only between the phone and the operator's base station in encrypted form. You can find out someone else's IMSI only by having physical access to their SIM card or having access to the operator's equipment.
Why are there dashes instead of IMSI in the phone settings?
This is due to Google security policies implemented in Android 10 and higher. The system limits application and user interface access to unique device identifiers to prevent the creation of digital fingerprints and surveillance of users.
Is it dangerous to share your IMSI with third parties?
Yes, this carries certain risks. Knowing the IMSI, attackers can theoretically use IMSI-catcher technologies to intercept traffic or determine your location. Never publish this number in the public domain.
Will the IMSI change when you port your number to another operator (MNP)?
Yes, when you change your operator, you get a new SIM card, even if the phone number remains the same. Since the IMSI is written on the SIM card chip, it will definitely change to a new one, issued by the new operator.
Is it possible to change the IMSI programmatically without replacing the SIM card?
On standard devices this is not possible. The IMSI is written to a secure memory area of the SIM card during production. It can only be changed with specialized equipment for flashing SIM cards, which is a complex procedure and often violates the terms of the contract with the operator.