‘Stealth Mode’ is the perfect way to keep your communications private. Once enabled, Stealth Mode can turn the selected number invisible. It can only be made visible again by disabling Stealth mode, See here.
Stealth Mode hides the number/category from the application's user interface and while it is in Stealth Mode all functions of that number are disabled until you enter your password and enable the number once again.
Warning! Do NOT forget your 4-digit password! This password is so private that the only person who knows it is you. So look after it!