It's been done already. A box consumers can buy for around £100 operates as a rule based filter for all incoming calls. The telecoms providers should have done more, and COULD do more than the basic offerings they have as add-ons to the service. Maybe they make so much money from carrying the robo calls that they are reluctant to put too much effort into it. There is much data available to the telecoms companies that they block from being received at the consumer's kit, and this limits what consumer fitted solutions could achieve.
The FTC can make quite an advance by passing a law that prevents the carriers from withholding associated data from the consumers' kit. CLI can be withheld by the caller, but the carrier still receives this data. It is blocked on privacy grounds, and replaced by a "withheld number" code, which limits the ability of rule based systems to tell the difference between a robo call with withheld number, or a family member using the service as a privacy measure.
The current option is to block all withheld numbers, which is a blunt instrument that could block legitimate calls. Spoofed caller ID is due to this blunt instrument being used by consumers to block marketing calls. To implement, the consumer would have to ask all callers to let their caller ID through, and this way they could generate a whitelist of numbers that will always be put through. The problem is that this would require the cooperation of callers, and robo marketers could discover some common numbers that everybody lets through, and uses them for spoofed caller ID.
I expect the solution would be software based, with the consumer buying a microcomputer powered "black box" that sits between the outlet and their phone. The software would be constantly updated as robo callers find ways around the system. It could have a "simple mode" for those who want to just plug it in and let it take care of itself, or an "advanced mode" for users who want to develop their own rules and filters.
This has already been done, the "Truecall" costs around £100 and does much of this. It requires Caller ID be passed by the carrier to the receiving equipment, and the cooperation of callers. It has both whitelists and blacklists, and calls can be routed to message, put through with a specific ring tone, or simply blocked. If a call gets through that the user didn't want, they can add the caller to the blacklist so that all future calls will be blocked.
It seems similar to spam filters for email.
The solution is not perfect, and never can be, just like email, Windows, or any other software based system.
Part of the solution lies in creating more robust international standards for carriers so that better data reaches the recipient, allowing such filtering kit to work better. Carriers could even be fined for not doing enough to prevent the use of their networks for carrying illegal calls.
The UK has a less draconian law, but even that is freely flouted simply by setting up the operation offshore. Oddly enough the US has been a source of illegal marketing calls to the UK, often the "boiler room" investment scams, although they seem to be coming out of Spain now, rather than the US.
$50,000 may only be "small change" to whoever wins the contest, as their prize winning system would gain considerable kudos just for being the winning entry, and they could make far more by selling it.
I am surprised the "Truecall" system has not done better, it seems to have been discontinued by many outlets, and is virtually impossible to get hold of in any major outlet. I have been thinking of buying one due to a sharp increase in robocalls coming about because of many government schemes, such as insulation grants, and PPI refunds. I hardly ever get calls from window and kitchen sellers any more