I read an email about doing this a while back. Never got around to it, though, I keep promising myself I'll share the joy of opening junk mail with the junk senders. Also, included in the email was advice on dealing with telemarketers. One was to keep an airhorn next to the phone! The other was to tell the person you were interested, but ask if they could hold just a moment. Then set the phone down and wait for it to make the 'please hang up now' noises. I've done that one.