If you follow an exacting script and keep careful records, you can apparently sue sloppy telemarketers (or their clients) for $500 each, and get free merchandise in the bargain. America's telemarketing laws seem tough on marketers, but they're structured in such a way as to make the process as difficult as possible for people who don't want to get phonespam. But if you are careful, you can get $500 every time a telemarketer calls you twice after being told to add you to its do-not-call list. They get to call you once without incurring this penalty, but apparently, you get to keep anything you order on the second call for free without paying for it, since "future calls will be a violation of an act of the U.S. Congress, any contract directly resulting from an illegal act is not enforceable. The Telephone Consumer Protection Act (TCPA) offers no 'grace period.'"
I'm not a lawyer, and I don't know if the author of the article is. It's presented in Comic Sans, so caveat emptor and all that.
Telemarketing Script (via Consumerist)
May I have your company's name, address and telephone number? If you are calling on behalf of a client, may I have the name, address and telephone number of your company, as well as the name, address and telephone number of the company that you are calling on behalf of?
Put me on your "Do Not Call List". You are hereby ordered to share my "Do Not Call Request" with your affiliates, associates, and related entities. If you are a third-party service bureau (telemarketing company), put me on your company's "Do Not Call List" as well as your client's "Do Not Call List".
Send me a copy of your "Do Not Call Policy". If you are a third party telemarketing service bureau, send me your company's "Do Not Call Policy" as well as your client's "Do Not Call Policy".
If you call me again, I will use your product or service and not pay for it. My denial of payment will be based on the fact that your future calls are a violation of an act of Congress, and any contract that is entered into as a direct result of an illegal act is unenforceable.
Do you understand what I have just told you?
Will you comply with my requests?