As soon as the pitch starts, I simply say " I'm not interested." and hang up. I don't wait for them to reply. As SOON as I've finished speaking, the phone goes back on the hook.
Same basic senario at the door. Not interested, door closes.
I had one guy knock again. I told him that I had expresed a lack of interest in his wares, that his persistance constituted tresspass after warning, and that I would now call the police.
He was gone from the neighborhood when they reached my house.