This is a third party collection agency. Once you tell them to no longer call you at your number (home, cell, or office) they must cease. Tell them you will call an Attorney (Attorney General) in what ever State you reside. If that doesn't work, file a complaint with the FTC (Federal Trade Commission) on line. Under no circumstances, reveal names, addresses or phone numbers. They want you to do the work even if they are on a "fishing expedition." If that does not work, let them know you are filing harrasment charges
against them. Their cost will be $1000 per incident plus all attorney fees. Most companies rely on a phone since they are too lazy to file properly.  Let them know that your attorney can play the same game. You will contact the US Congress will impose a maximum fine against them. Contact your US Representative (House and Senate). Also contact the local BBB and Sheriff Office.

Call received from John Linquist, very rude, on June 18, 2010.

Called my office looking for someone who's never worked here. I said "there's no one here by that name," they thanked me, and hung up.

These collectors rarely use their real name so you can not identify them if the matter goes to court when you sue them for harassment.  This practice is illegal and if you have the time file a complaint.

Called my new phone number looking for some stranger and I said that they had the wrong number and the lady kept pressing if I knew this person and I said again that they had the wrong number and she started to get very rude and I hung up. I blocked them right away because I'm not going through this harassment again from vulture debt collectors after changing my phone number because of these bottom feeders.