Check this site out. It should be something to keep those phone phreakers out of trouble/busy (relatively)
Sound Boards
They take celebrity's voice's from T.V. and prank call people.
NOTE: I do not condone this act, if it is unlawfull in you're area don't use it. It is supposed to be for personal entertainment only anyway. (Like calling you're friends and scaring the crap out of them)