Spoofed Caller ID. Whether it be a debt collector or a telemarketer who calls:
Make it illegal and punishible as a local and federal crime to call ANY individuals and/or businesses using a "spoofed" caller ID telephone number that cannot be called back to reach that exact individual or that individual's physical company/work location.
Furthermore, it should be law that anyone making an unsolicited call must identifiy themselves immediately and provide a valid call back number.