Effectively puts your phone in a "Do Not Disturb" mode where no one can reach you.
If you lend your phone to someone, you can bar outgoing calls to ensure they don't rack up a massive bill. How to Setup Call Barring The process varies depending on your device and carrier: On Android: Open the Phone app . Tap the three dots (Menu) and go to Settings . Tap on Supplementary Services or Calling Accounts . what is call barring