Secret codes of smartphones: Hidden ways to check the screen, battery, and system

11 October 2026, 21:54·54·Technology

Although modern smartphones have become an integral part of our daily lives, many useful features inside them are not visible in the standard settings menu. Especially when buying a used phone, special engineering codes come in handy to determine the condition of its screen, sensor, camera, or battery.

By entering these hidden USSD codes into the phone's call (dialing) screen, you can activate the device's hidden capabilities and diagnostic menu.

Diagnostic and test codes for top Android smartphones

Various manufacturers have introduced separate verification combinations for their devices:

Samsung: *#0*# — Menu for full testing of screen quality, sensor performance, camera, speaker, and vibration systems;
Xiaomi and Poco: *#*#6484#*#* — CIT menu to check all main parts and sensors of the smartphone;
Redmi: *#*#64663#*#* — Comprehensive hardware-level diagnostics of device components;
Realme and Oppo: *#899# — Engineering and general test menu; additionally, on Oppo, the *#808# code serves to check the screen, sensor, LCD, and camera;
Huawei and OnePlus: *#*#2846579#*#* (Huawei) and *#*#2346579#*#* (OnePlus) — System settings, engineering menu, and verification code;
Vivo and iQOO: *#*#225#*#* — View calendar and synchronization data;
Motorola, Lenovo, and ASUS: *#*#4636#*#* — Detailed technical information about phone status, cellular network, Wi-Fi, and battery;
Infinix: *#07# — Find out certification and radio emission (SAR) levels;
Tecno and Honor: *#85# (Tecno) and *#*#2345#*#* (Honor) — Model-dependent verification functions;
Sony: *#*#7378423#*#* — Service and diagnostics section;
HTC, Alcatel, and Lava: *#*#3424#*#* (HTC diagnostics), *#2886# (Alcatel test menu), *#1234# (Lava software information).

Special combinations for iPhone users

Apple devices also have useful commands that allow you to monitor network and communication status:

Knowing the IMEI number: *#06# — Displays the device's unique international mobile equipment identity (IMEI) number (this code works on all phones);
Field Test Mode: *3001#12345#* — Shows in-depth technical indicators about mobile signal strength and network coverage;
Check call forwarding: *#67# — Check which number calls are being forwarded to when the line is busy;
Find out all service routing: *#21# — Determine if calls and messages are being forwarded to another number;
Number display/hide status: *#31# — Check number hiding settings for outgoing calls.

Important note for users

When using these codes, several aspects should be kept in mind:

Model dependency: These combinations may change or fail to work on certain models depending on the region of manufacture, operating system version (Android/iOS), and processor type;
Precautionary measure: It is recommended not to change settings without understanding them when entering engineering and test menus, as this may lead to device malfunctions.