Personally i have a few that I use. I know its not very nice to mess with them, but I just can't help it.
I live in Aus BTW.
TM: Hi, I'm (insert name) from (insert company), I was just calling to notify you that you have been selected as a recipient of a free (apparently great deal).
Me: Oh great! go on..
TM: Well today we have on offer blah blah blah
Me: wow! I never knew I could get that here. I never seem to be able to find such great deals like this here in Indonesia.
TM: sorry sir? Indonesia..?
Me: ahh, yea, whats wrong with Indonesia?
TM: I was under the impression you were in Australia
Me: What gave you that idea? Thats a little stupid. Call a regular Indonesian man, on a regular Indonesian number and think that he's in Australia.
TM: Umm, are you sure sir?
Me: Well, Im pretty sure I know I where I live.
TM: ahh.. umm..
Me: Well anyway, do I get (insert offer) or not?
TM: Im not sure if that is possible (confused tone) AND/OR states their confusion
This goes on until they realise or when i get bored and hang up.
The other is that if any company calls up for someone tha has used our number (ie my uncle lol) for unpaid/late paying of bills.
Person on the phone will ask for (insert name) and i respond with saying that it is I.
Caller: Well sir, we have that you are overdue in your (insert payment).
Me: Listen, every month i put all my bills i can affod to pay in to a hat, and pick out a few to pay. If you people keep harassing me your bill wont even go into the F*#kin hat.