If you do not want to let the interlocutor know your telephone number, for a matter of confidentiality or not to be called back, the procedure is very simple.

First of all, if you plan to make more than one call with this system, you should open the phonebook and add it to the list of names: Darkening my number. In this way, next time, you do not have to consult the Internet to remind yourself how to do it.

Before the number you want to call, write #31# and "Unknown number" will appear on your interlocutor's phone.