Code: ##3282# or ##3282w/call
Typing - ##3282 or ##3282# - Field Test.
Description: These devices have the ability to manually change their network type "2G, 3G, or LTE". ##3282+ taping Call works on L920.
Code: ##MFG# that is ##634#
Typing ##634# - Color Variant + Life Time Counter
Description: Displays the multivariant color and life timer.
In some Windows Mobile Phone for Nokia Lumia, ##634# is a hidden code that can enable diagnostics tool.
How to Access the Diagnostics Tools
Open up your Phone Dialer in your phone, press the code ##634# , it will load up the tools.
Diagnostics Tools List
Accelerometer,ALS, Audio Loopback, Bluetooth, Camera, Battery Status, DTMF, Hardware Buttons, Headset Detection, LCD White, Lights ,Magnetometer ,Power Source ,Proximity ,Speaker ,Touch ,Vibra.
Usage of Diagnostics Tools ?
Those tools just let you to test out is all the hardware of the phone working or not. You may use this to check your phone to make sure that all of the hardware are working correctly, like Camera, or died pixel on your LCD screen and others.
Code: ##4678255#
Typing ##4678255# - Tier3 Status
Description: Silent Installer Component - aka Tier 3 (Launches a screen titled Tier3 Status and displays several OEM installed apps)
Code: *#07# or ##07#Typing *#07# or ##07# - Launch main page of extras+info
Description: The code is purposely written to keep all elements on the main
page to a "Collapse" visibility (meaning hidden). All the information
would be normally displayed when launching the "extras+info" application is in fact populated.
Code: ##PST# (##778#) Typing ##778# - Product Support Tool
Description: Has the same function on various WP devices; allows access to cell network settings. Uses a pass code of 000000. No fields are editable.
Code: *#06#
Typing *#06# – IMEI no. of your mobile