Under the Fair Debt Collection Practices Act, debt collectors can only communicate with you or your attorney about your debt. There's a very narrow exception that allows debt collectors to contact third parties, such as your parents, but only to obtain location information. Location information means your address and telephone number. During this conversation, the debt collector must tell your parents that he is attempting to confirm your location information, he can't tell them that you owe a debt, and he is only allowed to identify his employer if asked. Of course, your parents have no obligation to give the debt collector your address and telephone number. And once the debt collector has your location information, there is no permissible reason under the FDCPA to contact your parents, or any third party for that matter. In other words, if you've already talked to a debt collector and he knows how to contact you, it's a violation of the FDCPA for him to call a third party because he already knows your location information.
It's fairly common for debt collectors to contact people's parents about their debt. And it's not just college students and recent college graduates. I've had clients in their 40's and 50's whose elderly parents were called by debt collectors. I suppose it's possible that some debt collectors contact consumers' parents by mistake. But I also think that some debt collectors call people's parents as a collection tactic to put pressure on the consumer to pay the debt. Either way, its a violation of the FDCPA, unless it falls under the very narrow "location information" exception described above.