Virtual Audio Cable (VAC) is a program which is useful for manipulating audio on your computer. With it, you do not need to worry about any of the "Stereo Mix" stuff that people talk about. You also do not need a microphone or any special type of sound card or other audio equipment.
Virtual Audio Cable is paid software, which means you either have to buy it or acquire it through other means (the latter option is easy to find). Make sure you get the right VAC! There are two programs called VAC! This is the one you want: http://software.muzychenko.net/eng/vac.htm. And this is the one you don't want: http://www.virtualaudiocable.net/.
To configure VAC (Virtual Audio Cable) for prank calling, there are four steps you'll need to do initially, and then there are also some steps you'll need to do each time you prepare for a prank call session.
- Install Virtual Audio Cable (referred to, from now on, as "VAC"), Skype, and Audacity.
- With VAC, create three (3) virtual audio lines. You may also need to restart your computer afterward.
- Set Skype's output to virtual Line 2 (instead of outputting to your speakers, which is probably the default). Set Skype's input to virtual Line 1 (instead of your microphone, which is probably the default).
- Set Audacity to record on virtual Line 3.
- Right-click on the sound icon in the bottom-right corner of your screen, and click Sounds. Click the Communications tab, and click "Do nothing." If you skip this step, Windows will automatically turn down your sound whenever you're in a Skype call, and you don't want that to happen.
- Set your computer's default audio output to vac's Line 1 (instead of to your speakers. change it back when done pranking).
- Run the Audio Repeater (included with VAC) program three times, configuring like so: http://oi37.tinypic.com/345k1fs.jpg
- Play your soundboards in Google Chrome, Flash, or wherever else. Be sure to hit the Record button in Audacity before you start calling.
- When you're all done, undo step 1 by setting your computer's default audio output back to your speakers. Otherwise, your computer won't have sound unless you have Audio Repeater running.