How to select and enter a code on Android: a complete guide

Mobile devices based on Android represent an open ecosystem that provides users with access to deep system settings that are often hidden from the eyes of the average owner. These settings are activated using special character sequences known as engineering commands or ADB instructions. Understanding how to choose and correctly enter such a code can save your phone in an emergency, improve the quality of communication, or conduct a detailed diagnosis of the hardware. USSD codes, engineering teams or ADB instructions. Understanding how to select and correctly enter such a code can save your phone in an emergency, improve the quality of communication, or conduct a detailed diagnosis of the hardware.

However, working with system commands requires extreme caution. An incorrectly entered sequence can lead to data reset, device blocking, or changes in critical parameters of the radio module. In this article, we will analyze all the legal methods for selecting and using codes, from simple service requests to advanced tools for developers.

It is important to immediately understand: there is no universal “master key”. Each manufacturer (Samsung, Xiaomi, Google) implements its own shell modifications, so the set of commands can vary significantly. However, there is a basic standard Android Debug Bridge and general principles for working with telephony that operate on most gadgets.

Basic USSD commands and service codes

The easiest and safest way to interact with the system is to use standard USSD requests. They are entered directly through the Phone application (dialer) and processed either by the SIM card or by the device’s operating system. These codes do not require obtaining root access and rarely lead to a breakdown of the smartphone if you do not use the full reset functions.

To quickly diagnose the state of the network and device, you can use a number of basic commands. For example, checking the IMEI helps ensure that the device is legal, and asking for balance or traffic balance works at the telecom operator level. Some codes allow you to hide or display the phone number when making an outgoing call, which is useful for privacy.

⚠️ Attention: Entering a Factory Reset code through the dialer will delete all your data without the possibility of recovery. Use such commands only if the phone is locked or for sale.

Below is a table of the most common and useful commands that work on most versions Android:

Command	Description of action	Risk level
*#06#	Display IMEI and serial numbers	Safe
##4636##	Phone and battery test menu	Medium
##7780##	Reset application and Wi-Fi settings (without deleting photos)	High
*2767*3855#	Full reset to factory settings (Samsung)	Critical
##232338##	Displaying the MAC address of the Wi-Fi module	Safe

It is worth noting that on modern versions Android (starting from 9.0 and higher) many old codes were blocked by Google developers for security reasons. If you enter a combination and it does not respond or simply disappears from the screen, this means that the manufacturer of your firmware has disabled this function.

Engineering menu and hardware diagnostics

For a more in-depth analysis of the operation of the smartphone, there is a so-called engineering menu (Engineering Mode). This is a hidden section of the system intended for service centers and developers. Here you can check the operation of the sensors, display calibration, battery status and radio signal parameters.

This menu is entered through specific codes, which often depend on the device processor (MediaTek, Qualcomm, Exynos). For example, for MediaTek processors, ##3646633##is considered a universal command. Once inside, the user sees tabs with technical information, changing which without understanding the essence can disrupt the operation of the modem.

• 📡 Telephony: section for setting the preferred network type (LTE, 3G, 2G) and checking the signal level in real time.
• 🔋 Power: information about battery voltage, temperature and charge cycles, useful in diagnosing rapid discharge.
• 📶 Connectivity: tests of Wi-Fi, Bluetooth and GPS modules to identify hardware malfunctions of the antennas.
• 🎨 Hardware Testing: testing of individual components such as vibration, speaker, microphone and light sensors.

Particular attention should be paid to the frequency settings section. Sometimes users try to “guess the code” to force 4G to turn on where it doesn’t work. In the engineering menu, you can select a specific frequency range (Band Selection), but an incorrect choice will lead to a complete loss of communication.

USB debugging and using ADB

When standard USSD commands are not enough, the tool Android Debug Bridge (ADB)comes into the picture. This is a powerful command line utility that allows you to manage your device from your computer. To “select” the required code in this context, you will need not to guess the combinations, but to know the specific ADB syntax commands.

To get started, you need to activate the developer mode on your phone. To do this, go to Settings → About phone and quickly click 7 times on the item "Build number". After the message “You have become a developer” appears, in the new menu, activate the item "USB debugging".

adb devices
adb shell pm list packages
adb reboot bootloader

Through ADB you can perform actions that are not available through the interface: remove system garbage (bloatware), make full backups of applications, change screen resolution or emulate keystrokes. However, this requires connecting to a PC and installing drivers. An error in the command syntax can result in the phone going into an endless reboot (bootloop).

⚠️ Attention: The interfaces of the “For Developers” menu may differ depending on the version of Android and the manufacturer’s shell. If you do not find the item you need, check the location of the settings in the official documentation for your model.

Using ADB provides almost unlimited possibilities, but requires technical literacy. Commands are entered in the terminal on the computer, and not on the smartphone itself. This is an ideal method for advanced users who want to clear the system of pre-installed operator software.

What to do if the computer does not see the phone via ADB?

Most often the problem lies in missing drivers or a faulty USB cable. Try replacing the cable with an original one and installing universal Google USB Drivers via SDK Manager. Also check if the “Always allow debugging from this computer” checkbox is checked on the smartphone screen.

Smartphone manufacturer secret codes

In addition to the general Android commands, each major vendor implements its own unique sequences. They are designed for specific tasks: checking build quality, running display tests, or obtaining detailed usage statistics. Knowing these codes helps to distinguish an original device from a counterfeit.

For example, devices Samsung have one of the richest sets of service menus. The code #0# runs an extended hardware test, where you can check each pixel of the screen for brokenness, test the sensor for multi-touch, and check the operation of all sensors. This is critically important when buying a used phone.

Smartphones Xiaomi and Redmi use the code ##6484## (or ##4636##) to enter the CIT (Calibration and Test) menu. Here tests are carried out on the camera, flash, gyroscope and even the compass. If any test fails (the screen turns red), this is a clear sign of a hardware failure.

• 📱 Sony: The code ##7378423## opens the service menu to check the SIM card, speaker and camera.
• 🍭 Google Pixel: Supports many standard AOSP codes, but has limited access to engineering settings radio module.
• 🌏 Huawei/Honor: use code ##2846579## to access project settings, reset and battery information.

Device owners Motorola should try the combination ##7287##, which displays information about legality device and certification status. This is useful when purchasing gray imported models to ensure their authenticity.

Compatibility issues and blocking codes

Over time, Google's security policy is becoming more stringent. What worked on Android 6.0can be completely blocked on Android 13 or 14. This is due to the fact that attackers have previously used vulnerabilities in the processing of USSD codes to steal data or remotely control devices.

If you enter a known code, and it simply appears in the dialing field as plain text and is not executed, then your firmware is blocking this request. In some cases, it helps to use third-party calling applications, such as QuickShortcutMaker or special launchers that may have access to hidden system activities.

It is also worth considering regional features. Firmware for the Chinese market often has a different set of commands compared to global versions (Global ROM). A code that works on a phone purchased in Beijing may not work on the same device, but with European firmware.

⚠️ Attention: Do not download applications from unreliable sources that promise to “unlock all secret codes.” Most often, this is malware that collects your personal data or displays intrusive advertising.

In the case of complete blocking of standard methods, the only solution is to obtain root access, which will automatically void the warranty on the device. Without superuser rights, many deep settings will remain unavailable on new versions of the OS.

Alternative ways to access hidden functions

If selecting codes does not produce results, you can use alternative methods for activating hidden menus. One of the most effective ways is to use Activity Shortcuts. Applications like Activity Launcher scan the system and show a list of all available menus, including those that do not have an icon on the desktop.

Having found the desired action in the list (for example, “Testing” or “Engineer Mode”), you can launch it with one click, bypassing the need to enter complex combinations of characters. This is especially true for modern shells, where manufacturers deliberately complicate access to diagnostics. Another option is to use specialized software for diagnostics, such as for Samsung or for general data. These applications legally request information from the system and display it in a convenient way, often providing more data than standard engineering menus.

Another option is to use specialized diagnostic software, such as Phone Info SAM for Samsung or CPU-Z for general data. These applications legally request information from the system and display it in a convenient way, often providing more data than standard engineering menus.

Is it safe to enter codes on a new smartphone?

Entering basic diagnostic codes (IMEI check, software version) completely safe. However, commands containing the words "Reset", "Format" or changing network parameters (Band Selection) carry the risk of data loss or communication disruption. Always check the purpose of the code before entering it.

Why does the code ##4636## not work on my phone?

Starting with Android 9, Google has limited access to this menu for third-party applications and in some firmware. On devices from Xiaomi, Samsung and other brands, access may be blocked by the shell manufacturer. Try using the Activity Launcher application to find the hidden menu.

Is it possible to unlock a phone from an operator using a code?

No, standard USSD codes cannot unlock a phone from being locked to an operator (SimLock). This requires a special unlock code (NCK), which is requested from the operator or purchased in specialized services, and is entered into the unlock code request menu.

What to do if after entering the code the phone rebooted?

If after entering the code the device went into reboot, but turned on normally, most likely a reset or configuration change command was applied. If the phone does not turn on (hangs on the logo), you will need to enter Recovery mode to reset the settings or flash the device.

Where can I find a list of codes specifically for my model?

The most accurate information can be found on the official support forum of the manufacturer of your model or in specialized threads on resources like 4PDA and XDA Developers. Look for the "Engineering menu" or "Secret codes" section for your specific model.