Usar la aplicación APKPure
Obtener All GSM Secret Codes versión histórica en Android
Para ayudar a todos los usuarios de teléfonos móviles.
The GSM standard allows most of the functions to be controlled by entering codes into the keypad of a mobile phone: you can set diverts and the like, accept or reject calls, or even change your PIN code by typing at the keypad.
Unfortunately, not all the codes listed here are enabled by every network. If a code isn't supported, it simply won't work