What you say is absolutely true and enforcable against "real" debt collectors such as yourself. However, we are more frequently seeing pretend collectors that are nothing but scams, often originating overseas, and typically pursuing invented and ambiguously described "debts." Enforcability of the FDCPA is nearly impossible in these situations. The purpose of my answer was to alert the asker to the possibility of a scam.

I agree that this was probably a scam. I have been faced with the same scams in the past. I usually make the same information request and state they they are in violation of the debt collection act. Soon thereafter they stop calling. Some will continue calling my private cell phone until I state that I am an attorney and that my next call will be to police. The purpose of my answer was simply to give guidelines of how to handle any debt collection attempt.