What is an MMI Code and How to Use it?

Modern smartphones may seem quite simple and easy-to-use on the outside but there is a whole lot going on in the inside. For example, whenever you touch your phone’s screen it launches a series of processes which record the action and communicate it to the kernel and hardware services. Fortunately, operating systems like Android and IOS facilitate the users by hiding all these complexities behind a clean and simple UI. But there are times when you want to dive into the complexities and change advanced system settings, that’s where the MMI codes come in handy.

So, what is an MMI Code and how to use it efficiently? This article explains all the dos and don’ts of MMI codes so that you don’t accidentally break your beloved device, let’s get started:

What is MMI Code?

MMI is a smartphone acronym that translates to Man-Machine Interface. These prompts are special codes that launch hidden settings and even facilitate sim operator actions. For instance, you can use various MMI codes to access diagnostic tests, view system information, change network bands, and even recharge your sim credit balance. 

There are hundreds of MMI codes which translate to a specific function of your mobile device. However, all codes must be entered correctly in the phone’s dialer application for them to work. For example, you can input “*#06#” on any mobile device to view its IMEI (International Mobile Equipment Identity). Similarly, you can try (*#0*#) on your Samsung phone to launch the diagnostics test menu. 

How to Use MMI Codes?

As mentioned earlier, there are hundreds of MMI Codes to launch various actions and menus. However, not all codes work on every device, except for a few universal codes (like *#06#). So, you should check your smartphone company and only use the codes provided in the official documents. Similarly, the MMI Codes for network operators depend on your region and network company (T-Mobile, Verizon, EE).

Once you obtain the required MMI Code for your mobile device, simply open the Dialer App and dial the code exactly as described without missing any part. If the code doesn’t work, try a different code for your phone model. Sometimes, the MMI Code requires you to call the number but that’s usually the case for sim-related functions. Otherwise, the code will automatically open the desired menu without placing a call. Finally, follow the on-screen instructions to proceed with the desired function. 

Beware, certain codes provided from third-party website may also potentially hack your smartphone. Therefore, it is important to only use the codes provided on the official websites of both your smartphone manufacturer and network provider.

What Can I do with MMI Codes?

MMI Codes can be pretty powerful in terms of functionality if properly used. You can use certain codes to view device information, system information, change network settings, enable call forwarding, conduct device diagnostic tests, and even interact with your network provider. Here are a few functions that you can perform with various MMI codes:

  • View Device IMEI: You can dial (*#06#) on any mobile device to view its IMEI. You can also match the phone’s IMEI with the box to verify that you phone isn’t refurbished.
  • Change Network Settings: You can perform various tasks like change preferred network modes, VoLTE, and enable 5G network bands. You can access this menu by dialing “*#0011#” on your Samsung smartphone (check your device code for other manufacturers).
  • Set up Call Forwarding: You can dial “*#21#” to temporarily or permanently forward all calls to another device. You can also view and change other settings for this feature.
  • Diagnostic Tests: Various phone manufacturers like Samsung, Huawei, and OnePlus provide built-in diagnostic tests menu in their devices. You can use these settings to verify that all sensors and hardware are functioning properly. Dial “*#0*#” to launch the diagnostic tests on any Samsung smartphone. 
  • Credit Recharge: Almost all prepaid network providers offer the service to recharge your account with card voucher numbers. These MMI codes are usually “*123*voucher number#”. However, you can also check with your network provider to confirm this code.
  • Access Hidden Settings: There are certain menus that allow Developers and Repair persons to change system settings and even install new firmware on your device. There are countless hidden settings in every smartphone locked behind special MMI codes. “*#9090#” is one such code used to access USB service mode on Samsung and other Android devices.
  • Root Android Phones: Root access isn’t really illegal unless used responsibly. You can gain Root access for your device by installing special packages from hidden menus (accessed via MMI codes).
  • Balance Transfer: Certain network providers allow their users to transfer prepaid credit to other users using the same company’s sim. You can check your network provider website for a list of MMI codes and transfer limits.
  • Network Account Information: You can view your data usage, available credits, current bundles, and even purchase a package for your sim. You can access these menus by dialing special MMI codes like “*124#” (check your network provider website for more information).

  • Precautions for Using MMI Codes:

    By now you understand what MMI Codes are and how powerful they can be if used properly. However, with great power comes great responsibility. Therefore, it is imperative to understand the potential risks that come with using such powerful codes. Here are a few precautions for you to keep in mind while surfing these settings:

    • Always confirm the MMI codes from your network providers’ and phone manufacturer’s website before dialing them (there’s no coming back).
    • Third-party MMI codes can allow potential hackers to access your device and network accounts, so keep away from such attempts.
    • Never give remote access to a potential service expert unless you verify their identity.
    • Certain network codes like checking balance, buying packages, and sharing prepaid credits have potential service charges (check your network provider website to confirm).
    • Changing system settings from Hidden Menus can potentially harm your device and even lead to system failure (they are hidden for a reason). Therefore, it is important to only change a setting after fully understanding its effects and risks associated with it.

    Lastly, always backup your device before changing anything in the hidden menus to create a safe restore point.


    This article provides an insightful guide to “What is an MMI Code and How to Use it?” Hopefully, now you have a basic understanding on this topic and the potential risks attacked to using such powerful codes. If you have any questions or thoughts feel free to reach out in the comments section.