Here is a good service that could be used to Prank your friend for a while. All you have to do is to just enter the phone number,display name,display number and the message. This service will call the destination number and a computer generated voice will read out the message. You can even select the voice. They bring you free phone calls using the latest text to speech technology.
Try it out by typing in the few required details and your prank call will be placed shortly.
I haven't tested the service, If anyone of you tested it please leave a comment about the service.
A Free service to prank your friend with a computer generated voice.