Incessant Calls

In doing some research, this company goes by a couple of different names and you will get calls from more than just this company if you are on their 'list'.  They are a company that buys very old debts from companies that have given up and written off the debt.  NetProCo 'buys' the debt and then has the right to start harrassing people to pay them NetProCo now.  The problem is that I imagine most of their numbers are wrong as the debt is so dated that they don't have the right number for the right person as numbers change. I get calls because my home office number that I have now, as this number used to belong to someone who apparently owed several companies money so I'm not surprised about now receiving these calls.  So most of us are receiving these calls erroneously as they are looking for someone that 'used' to have our phone number.   I have not figured out how to make the calls stop, though, but this is why someone is receiving these calls.  They also call by a 1.800 number and a different name which I don't remember offhand, but it's the same related company apparently.