For five years, when I moved into my house, I was harassed by all kinds of bill collectors because I inherited a number that belonged to someone who defaulted. It was aggravating, because they did not beleive that I did not know the person they were looking for. Eventually, it got so bad, I had to find out my rights, and threaten to sue. They stopped after that.
Collection agencies are scum bags. They rarely follow the law and they prey on people's ignorance. They do not care who they are talking to. My brother is the biggest dead beat, but some how he keeps getting credit card offers and taking them. My poor parents, they get these calls and have been getting them for 20 years!!
I know me personally, I would never talk to any one over the phone in this regard. If they really want something, they will sue me and have me served. Then, I will show up to court with my attorney and have them handle everything.