I picked up and courteously said Hello 3 times. But ..... No response. If these callers cannot be polite enough to respond, they should be aware that they are losing people who have been good supporters of their charity.
^ I'm going to take vc's word for it. Just on the off chance that someone from the Kidney Clothes Line is seeing this listing, you might have better success if you actually have call display say who you are. Or better still, put some hampers in the local malls because these days phone solicitation has become invalid due to the scammers ruining it for everyone else.