Business Idea:

Instead of the government doing this (and being self-funded), why not do it commercially? Just set up thousands of personal phone numbers (honeypots) and just wait for the calls to roll in.

Naturally issues like tracking down the callers and filing mass lawsuits would generate problems the startup would have to overcome, but you'd be at an advantage because you'd have plenty of data at your disposal. Eventually you'd learn more about the branch of law that deals with these infractions and how different jurisdictions handle the cases.

What are the ethical side effects?

1. If your business became large enough, and it became a realistic outcome that telemarketers who use illegal tactics would have to pay damages like the 4k one in this article, the ROI for telemarketing may decrease to the point that it's not used any more.

Can I register my business phone number or a fax number?

The National Do Not Call Registry is only for personal phone numbers. Business-to-business calls and faxes are not covered by the National Do Not Call Registry.

You could try a more complicated approach: sell consumers a device which records their calls locally, and sign them up to the do-not-call list. The device would have a spam button; when pressed it would send the caller id + recording of call to your company's servers. The company would use this to help the customer threaten or sue telemarketers, splitting settlement/lawsuit revenue.

This would be illegal in many states, but you could restrict it to states with one-person consent to record conversations.