How to enable Private Mode ?

(From the mobile application only)

From the home screen, open the left-hand pane via the side menu ☰ top left,
Scroll down to the "Options" menu under your number, then go to "Number settings".
Activate "Private Mode" and choose a 4-digit code.

⚠ You're the only one who knows this secret code, so don't forget it!

Go back and you'll see "Private Mode activated" appear under your number.
All you have to do is press "hide" to make it disappear.