Dial *67 before the phone number you want to call
Use #31# before the phone number if your carrier supports it
Enable caller ID blocking in your phone settings
Turn off caller ID for individual calls through your carrier app
Contact your mobile carrier to activate permanent caller ID blocking
On iPhone, go to Settings > Phone > Show My Caller ID and turn it off
On Android, open the Phone app, go to Settings, then Caller ID, and choose Hide number
Check whether caller ID blocking is supported in your country or by your carrier