I'm also on the TPS and it stops most calls, except the ones that come from overseas, and those annoying recorded message ones. I get extremely few though.

My brother has a printed sheet which is like a flow chart on how to respond to a cold caller - a bit like the scripts they are supposed to stick to. For every thing they say, it has a way of drawing them into a conversation that has nothing to do with their product. It is hilarious listening in to him when he is answering one of these calls. I will have to see if I can find it on-line.

Bagpuss