VoIP Clearing House
Illegal robocallers almost universally use spoofed phone numbers, which generally run through VoIP, or voice over Internet Protocol. This makes it impossible to identify the caller to file a Do Not Call complaint with the FTC.
I propose the creation of a VoIP Clearing House (funded by fines for Do Not Call violations) through which legitimate VoIP providers such as Skype could route calls. The calls would be required to leave an IP address trail similar to the ones that appear in E-mails, and that are used to identify the origin of spam E-mail. If a Do Not Call complaint was filed, the clearing house would be required to provide the IP address to the FTC (including the date and time of the call).
Whoever wanted to place a VoIP call through the clearing house would therefore have to have a traceable IP address (again, just like the one that appears in the full headers of an E-mail). This would ensure that every call through the clearing house will be traceable to an identifiable caller. If a Do Not Call violation complaint was lodged, the clearing house would provide this information to the FTC to allow enforcement of the civil fine for the violation.
Phone companies could then be required to block, at the customer's request, all VoIP calls that have not gone through the clearing house--or phone companies could even elect to not accept under any circumstances calls that are not traceable to an identifiable source. Calls to emergency numbers (e.g. 911) should be required to go through the clearing house, to prevent criminals from placing untraceable false alarms to agencies of public safety.
I doubt that Rachel from Cardholder Services, or the telemarketers who are currently advertising "free" security systems (both in violation of Do Not Call as well as regulations against robocalling) will place any calls through a system that requires traceability of this nature. In addition, this would make it impossible to use an untraceable VoIP phone to make a terroristic threat or commit a similar crime.
DOES IT WORK? From what I know of the Internet, IP connections are traceable. There is however such a thing as IP address spoofing. An additional security layer could be added by requiring sellers of VoIP services to register with the clearing house, and to provide some kind of password (automatic, shared between the VoIP vendor and the clearing house) for each call to prove it is really coming from the VoIP vendor and not somebody who is spoofing its IP address.
IS IT EASY TO USE? The end consumer (person being called) would not even notice the difference because the illegal robocalls would be blocked by the phone company--or, if one was not blocked, it would have gone through the clearing house and could then be reported.
CAN IT BE ROLLED OUT? It does not appear to require any technology that does not already exist.