Dial *67 before the phone number on most North American carriers
Dial #31# before the phone number on many international carriers
Check your carrier’s caller ID blocking code if *67 or #31# does not work
Use your phone’s settings to hide your caller ID for all outgoing calls
On iPhone, go to Settings, Phone, Show My Caller ID, then turn it off
On Android, open the Phone app, go to Settings, Calling accounts, Additional settings, Caller ID, then select Hide number
Use a VoIP or calling app with caller ID blocking options
Contact your mobile carrier to request permanent caller ID blocking
Verify the number is blocked by calling a different phone or asking the recipient to check caller ID