This gets a bit tricky these days with caller ID and *69. I have heard of people prank calling someone and then getting a callback...doh!
-frick
This happened to me once, I found some number on a bathroom stall so I called it up claiming to be a doctor with the results to her pregnancy test. Anyway within 5 minutes of hanging up her "boyfriend" called and started bitching at me. It was quite hilarious.