I just tell them that I'm not interested. I don't wanna interfere with their jobs, and waste their time by trolling them. They probably want to be doing the job as much as you want them to call you. But if they call multiple times in a day, then I might troll them.
They ARE doing their jobs but when I say I am not interested, I expect them to say thank you hand hang up..that never happens, especially with bill collectors that call about a guy name juan (i guess he had the previous number) they insist that I am lying about who I am..I just say "nonononoonono" over and over until they hang up. My dad just sets the phone by the TV and turns it up..
I bullshit them so hard.. I make them think I'm genuinely interested in their product, then I tell them to fuck off in some bizarre way.. I should record some of them..
I have no need to troll them, I just notice that it's someone that I don't want to answer, and pick up, and then hang up, and then they don't call again.
Works every time.