I usually have a bit of fun with them, for instance, i will ask them how there doing, how there day has been. Then I will try do them a deal, i.e 'Tell you what, i'l have one of these phones if you buy x amount of x from my buisness.' This usually confuses them a fair bit, but because your not being rude or offensive, there not allowed to hang up. So you continue to ask random questions, or give statements like, weathers nice today, how is it in india? etc etc