If you're just doing regular prank calls from domestic residence to another you can dial *67 to hide your phone number. This is a FREE service that is put in place to encourage privacy in the telephone system. Conversely, when you're NOT making crank calls, someone might tell you to dial *82. *82 is to DISABLE your privacy and show the number you're calling from to the recipient. If you like making funny phone calls, STAY AWAY FROM *82 like the plague. Even though *67 is usually pretty effective, it is only a superficial means of hiding your identity. If you really want to hide your identity, of even change it, you need a service like SpoofCard which is like .06c / minute. (A small price to pay...)