How to find secret codes (entered via the dialer) in Android apps

"To find all "Secret Codes", special properties and other hidden phone features and settings, used in the GT-I9300. The secret codes are not so secret, but
are often used to activate and manipulate many settings, such as debug modes, network connections, factory test modes etc. It is an unfortunate choice of
words but we will stick to this definition nonetheless for simplicity, since it is also used in the source code by Samsung and AOS. Do not confuse secret
codes with VSC (Vertical Service Codes), USSD (Unstructured Supplementary Service Data) or other MMI (Man Machine Interface) codes.

Although there are many "standard" codes common to many Samsung phones, they do vary to some extent. This is because their functionality often depend on
the particular hardware, in particular the baseband processor (aka radio, DSP, BP or CP) and the multiplexer chips that switches the various internal USB paths, for example between MHL, BP and AP.

This is an informative reference thread on these features. If you have relevant additional information you'd like to share, please post it here."

To trigger secret codes via a shell command, execute this:
am broadcast -a android.provider.Telephony.SECRET_CODE -d android_secret_code://1111

Replace "1111" with your secret code (eg. SuperSU can be launched with the secret codes "1234" and "supersu" ... the latter corresponds to the numbers "7873778" on your dialer keypad). To trigger secret codes via the dialer, prefix them with "*#*#" and suffix them with "#*#*" (some phones require only "*#" and "#*").