Dial *67 before the phone number you want to call
For some countries, use the local caller ID blocking code before dialing
Go to your phone settings and turn off caller ID for outgoing calls
On iPhone, open Settings, tap Phone, tap Show My Caller ID, then turn it off
On Android, open the Phone app, go to Settings, tap Calls or Calling accounts, then Caller ID, and choose Hide number
Contact your mobile carrier to request permanent caller ID blocking
Use a VoIP app or service that supports hidden caller ID
Check that the number is not blocked by the recipient’s phone or carrier settings