This is a debt collection agency. They don't leave messages because somehow you are related to the person they are looking for and they cannot give any information if it is not the one they are looking for. They just ask if you are the one they are after and if not they leave you alone for a while. They call back to see if you can help them out.
Called and left a wierd broken up automated message looking for someone I don't know.. I called back to find out that it's Cingular Wireless Collections. Never had an account with Cingular..... Only Sprint. Told them to quit calling. We shall see what happens