Android and Samsung Secret Codes USSD and MMI Code List

Android phones and Samsung Galaxy devices hide diagnostic menus and network tools behind short dialer codes. These are known as USSD (Unstructured Supplementary Service Data) and MMI (Man-Machine Interface) codes, and you type them straight into the phone app to pull up system info, run hardware tests, or check carrier settings.

The catch in 2026 is that fewer of these codes still work than older lists claim. Manufacturers and carriers have disabled many of them for security reasons, so the list below sticks to codes that are still confirmed working, with clear notes on which ones are blocked or risky.

For the iPhone equivalent, see our iPhone Hidden Secret Codes USSD Code List. This guide covers Android and Samsung only.

MMI Codes Versus USSD Codes

MMI codes are device codes. They tell your phone to open a hidden menu built by the manufacturer, like a hardware test screen or a service mode. These work offline because nothing leaves the phone.

USSD codes are carrier codes. When you dial one, the phone sends a request over the network to your carrier and shows a reply, such as your call forwarding status. These need an active mobile signal and will not run over Wi-Fi only.

Most codes run the moment you finish typing. A few need you to press the call button. If a code returns "Connection problem or invalid MMI code," your phone, Android version, or carrier does not support it.

Phone and Software Information Codes

These read-only codes reveal hardware and firmware details and are safe to use. They do not change any settings.

*#06# shows your IMEI, and on most phones the serial number too. This is the one truly universal code and works on every Android phone, including Pixel and Samsung.
*#1234# displays the firmware versions on Samsung devices (AP, CP, and CSC builds).
*#12580*369# shows hardware and software details such as the manufacturing date on many Samsung models.

On a Samsung Galaxy, *#1234# is the reliable way to confirm exactly which firmware build you are running before an update or repair.

Hardware Test Codes

If a button, sensor, speaker, or part of the screen seems faulty, a test code lets you check the hardware directly.

*#0*# opens the general hardware test menu on Samsung Galaxy phones. From one screen you can test the display colors, touch response, sensors, vibration, speakers, microphone, and cameras.
*#0283# runs an audio loopback test for the microphone and speakers on Samsung.
*#0842# tests vibration and screen backlight on Samsung.
*#2663# shows the touchscreen (TSP) firmware version on Samsung.
*#*#4636#*#* opens the Android "Testing" menu with phone info, usage stats, and Wi-Fi details. It is part of stock Android and works on Pixel and many other phones.

Important note for Samsung owners: the default Samsung phone app blocks *#*#4636#*#*. To use it, install the Google Phone app, set it as your default dialer, then enter the code there.

Network and Service Codes

These codes open low-level network and connection menus. They are mainly useful for diagnosing weak signal or USB connection problems.

*#0011# opens Samsung service mode, showing real-time signal strength, network type, and band information for 2G, 3G, 4G, and 5G.
*#9900# opens the Samsung SysDump menu for collecting diagnostic logs. It is read-only and is mostly used by technical support.
*#0808# opens the USB settings menu on Samsung, where you can switch the USB mode. This is an advanced tool, so leave it on the default unless a technician guides you.

On newer Galaxy models such as the S24 and S25 series, Auto Blocker can stop some of these codes from running. If a code does nothing, turn the feature off temporarily.

Settings > Security and privacy > Auto Blocker

Call Forwarding and Carrier Codes

These are true USSD codes that talk to your carrier, so you need a mobile signal. They are handy for checking whether calls are being silently forwarded and for clearing forwarding rules.

*#21# shows whether unconditional call forwarding is active (all calls diverted).
*#62# shows where calls go when your phone is unreachable.
*#67# shows forwarding for when your line is busy.
*#61# shows forwarding for when you do not answer.
##002# cancels all call forwarding rules on GSM carriers at once.

Dialing *#62# only reports your forwarding settings. It does not tell you whether your phone has been hacked, despite what some viral posts claim.

Codes for Other Android Brands

Many codes are brand-specific, so a Samsung code may do nothing on a different phone. A few that are commonly reported as working:

*#*#7287#*#* opens the hardware diagnostics menu on Google Pixel devices.
*#899# opens engineering mode on several OnePlus, Oppo, and Realme phones.

Because behavior varies by model, Android version, chipset, and region, treat any unfamiliar code as model-specific. The universal *#06# IMEI code is the safest one to rely on across brands.

Reset Codes and Why to Avoid Them

Older lists include reset codes such as *#*#7780#*#* and *2767*3855# that wipe the phone. The second one triggers a full factory reset with no confirmation prompt, so a single mistyped entry could erase everything.

On modern Samsung software (recent One UI builds), both of these reset codes have been disabled to prevent accidental wipes. That is a good thing. There is no reason to use a hidden code to reset a phone.

If you genuinely want to reset, use the built-in menu instead, which warns you first and lets you back up.

Settings > General management > Reset > Factory data reset

How to Use Secret Codes Safely

1.Open the phone app and go to the dial pad.
2.Enter the code exactly as shown, including every star and pound sign.
3.Stick to information and test codes unless you know exactly what a code changes.
4.If a code does nothing, it is likely blocked, brand-specific, or unsupported by your carrier rather than broken.
5.On a Samsung, try the Google Phone app for stock Android codes, and disable Auto Blocker if a service code will not open.

Used responsibly, these codes are a quick way to check your IMEI, test failing hardware, and confirm whether your calls are being forwarded, all without installing anything.

Frequently Asked Questions

Why do my Samsung secret codes no longer work

Samsung has disabled many codes in recent One UI updates for security. The default Samsung dialer also blocks stock Android codes like *#*#4636#*#*, and Auto Blocker on the S24 and S25 series can stop service codes from running.

What is the difference between a USSD code and an MMI code

An MMI code opens a hidden menu on your phone and works offline. A USSD code sends a request to your carrier over the network and needs an active mobile signal, so it will not work on Wi-Fi alone.

Is it safe to use these codes

Information and hardware test codes such as *#06# and *#0*# are safe and only read data. Reset codes that wipe the phone are dangerous, which is why modern phones disable most of them.

How do I check if my calls are being forwarded

Dial *#21# to see if all calls are diverted, or *#62#, *#67#, and *#61# for conditional forwarding. Dial ##002# to cancel all forwarding rules on a GSM carrier.

Do these Android codes also work on iPhone

No. iPhones use a different set of dialer codes. See our separate iPhone Hidden Secret Codes USSD Code List for those.

Why does a code show Connection problem or invalid MMI code

That message means your phone, Android version, or carrier does not support the code you entered. Double-check the code, and on Samsung try the Google Phone app or turn off Auto Blocker.

First published October 14, 2025. Last updated June 4, 2026.