Dial *67 before the phone number for that call
Use your phone’s call settings to enable “Block Caller ID” for outgoing calls
For Android: Settings → Calls → Additional settings → Caller ID → Hide number
For iPhone: Settings → Phone → Show My Caller ID → Off
Use your carrier’s “Caller ID blocking” feature (request activation)
Use your carrier’s app or website to enable “Hide number” (if offered)
Block the number permanently by setting “Hide number” in your device settings and leaving it enabled