I have found that when you start asking for the names of the callers and tell them why (future lawsuit) they start getting all nervious. If they want to give you their ID number my response has been" Oh an ID number. I do not know an ID number and besides you called me by my name and you telling me I can not know your name? What kind of business is this anyway? You say you must use an ID number for your protection? What is it that you doing that you need protection from? Harrassing people?" This one has worked for me.
