I always ask open ended questions of the caller. ex: Do you still pick your nose? What are you wearing on your head? Did you see "Raising Arizona"? Who will win the World Series? How much do they pay you? Have you ever had a real job? etc.. If that doesn't work hold the phone by the toilet and flush.
I guess for whatever reason, I showed up as unregistered. Probably because I recently moved. Makes sense I guess.