1. If you want to block your cell phone number on a call by call basis, dial *67 before entering the number. For example, you would dial *67 (123)456-7890.
2. Unfortunately you will not get any confirmation that it worked, so I would test it once before to make sure it works with your cell phone provider. This way you can confirm that your number is blocked.
3. If you want your cell phone number to show up as private or blocked permanently, call your service provider (usually by dialing 611 on your phone) and ask them to block it. They usually can process these requests the same day.
* Remember that a lot of people don’t answer calls from numbers they don’t recognize so think carefully before blocking your number.