One of the biggest problems with winding up on the wrong end of a collections bill is that the lender is usually long gone, having sold the debt to some sketchy collections agency that ignores the Fair Debt Collection Practices Act (FDCPA).

The FDCPA has some real protections! Some features:

* You can't contact someone other than the debtor (like their boss) and mention a debt. (You can only say that you're "trying to confirm X's phone number" etc.)

* You can't call after 9pm

* If the debtor asks to not be contacted in any channel other than mail, you must acquiesce immediately (though I think it needs to be in writing)

* If the debtor asks not to be contacted at work, you must respect that

The CFPB has a page on protections: https://www.consumerfinance.gov/ask-cfpb/category-debt-colle...

And wikipedia has more: https://en.wikipedia.org/wiki/Fair_Debt_Collection_Practices...