As an update to my previous post, there is apparently some movement afoot to implement a method of secure verification of caller ID info. It is similar to how e-mail and websites are encrypted and authenticated, using certificates.
STIR/SHAKEN is a technology standard that incorporates an authentication service, a verification service, and a certificate repository. When a call is made, the authentication certificate issued by the caller's provider is looked up by the recipient's provider, and the call info is verified as being authentic or not.
The standard appears to be designed to be implemented at the service provider level. As I stated previously, carriers will be slow to adopt anything that will cost them money, due to the amount of power they wield, and this case is no exception. The call for them to adopt such a standard was put out by the FCC in 2014. Nonetheless, 5 years later some providers, including Verizon, are going public with announcements that they intend to implement this standard, which would conceivably have a major impact on the type of robocalling - and by extension, the entire robocall industry. By preventing the misuse/abuse of caller ID information, customers can then, in turn, effectively utilize tools such as spam filters to recognize and block calls from spammy sources.
As for when this all happens, Verizon says that in March, 2019 they begin offering their anti-spam service for free for their wire-line customers, which they say supports the STIR/SHAKEN call authentication. Even if you are not a Verizon customer, it is a good thing for it to be adopted by any of the big providers. At worst, it will reduce the cost effectiveness of these robocalls, and the volume will begin to drop, which will affect everyone.
Let's all hope this happens without a hitch, and our telephone infrastructure can become sane again.