I'm immune to this one...

I'm basically immune to this trick, as I have acquired BOFH-level treatment for telemarketers:

Caller: Hi, is this <unkown person>'s house?

Me: No. <SLAM>

Caller: Hi, is this (my name)

Me: Yes

Caller: Hi, we're calling from HSB.... <SLAM>

You can be as rude as you want to telemarketers as you like. I used to redirect my landline to my mobile, but after 5 days of cold calls, I decided to cease this practice. Good thing I can't get cold callers on my mobile :)