Re "A chum of mine talks to them... and gradually talks quieter and quieter until he can tell that they've turned thier phone reciever volume WAY up...

Then he blows a ref whistle as loud as he can into the phone..."

Sounds like an urban tale to me, but if it's true, it's really ignorant and nasty. You can destroy part of a person's hearing that way. Tell the a**hole to say "Put me on the do-not-call list."