I want to make a call log screen for my client

Hello I am making a app for my business man client he want to make his own call log app for there tele caller employee. He don’t want to show his client phone number to his tele caller employees.
So I have decided that he will not use there pre install call dialler app. And use my call log in which I will hide my clients phone number so that my employees will not able to see the number.

This is not possible

if true caller can to it way we not

TrueCaller is Made in Android Studio Its Developer Did not Create in MIT app inventor Distros It Is Impossible As @Faraz_Firoz1