How to block or unblock my mobile phone number when making an outgoing call
To block your mobile phone number on a per-call basis, dial #31# before each phone number you call.
To permanently block your number use your Call Settings menu.
Get step-by-step instructions for your device on how to hide your caller information.
If you have permanently blocked your number, you can unblock it on a per-call basis by dialling *31# before you dial each phone number.