Debt collectors are actually more regulated than telemarketers, so once they are convinced you aren't the debtor, they will stop. I think the not wasting time on pointless calls is even more important to them than marketers. Even in the case that they are contacting the debtor, there are pretty strict rules they must follow.

I guess this discusses some aspects of it: http://blog.credit.com/2011/04/getting-collection-calls-for-...