What do you enter when when you are masking your phone number when calling someone else?

To make you phone number anonymous on another's caller ID, what do you enter? And in what order: before dialing the phone number, while dialing a phone number, or after dialing a phone number.

I think it's *87 or something like that.

*67 will make your number Private...it will show on their caller id as private, or unknown.

Before you dial the number you intend to call press *67 then the number. that should do it (: