Mark wrote
Nightjar wrote
Andrew Gabriel wrote

...? I must think up some response which is going
to take half an hour to explain with no opportunity
for interruption, but I haven't done that yet....

Mine is 'I don''t take cold calls. Goodbye', followed by putting the
phone down. I don't see the point in wasting any more time than that.

And I omit the "Goodbye" and hang up straight away.
But I don't usually answer calls with no displayed CLID.

Thats a dangerous approach. Sometime it could be the hospital
saying that someone you care about has just been run over etc.

And one time I had the cops call me one Saturday morning saying
that they had grabbed a couple of stupid kids who had quite literally
been walking around the streets late at night, filling it with what they
could find in the cars they came across and suggesting I might like to
come down to the cop shop and pick up what they had got from my car.

I'd managed to leave the passenger's door unlocked because I had
bought some beer at a drive thru bottle shop on the night before.