Since it is almost 2010, my last post involved changing your caller id, so you can prank your way into the new year. This new service called caller id faker lets you change the number on your caller id and even disguise your voice. The only catch is that you need to listen to two advertisements. After that you can prank as long as you want.
There are also other services that let you change your caller id such as prankdial. This website has prerecorded voices that you can have call from any number that you can choose to fake, and even download the call after it is completed.
Sure this service is going to annoy many people, and abused with the wrong purposed the caller id faker could change your caller id to any number, so impersonating someone, while funny, could be used for the wrong purposes.
Change Your Caller Id With Caller Id Faker found via this link