The real problem is the lack of security and authentication on telephone networks, which enables number spoofing with virtually no chance of reprisal -- foreign callers (realistically out of the FCC's jurisdiction) use VoIP services to create calls that originate from an IP address from the telephone network's perspective, and the phone network makes no attempt to authenticate the metadata (like the phone number that…
What I don’t understand is why no major mobile carrier is offering a solution to this. It’s a pretty competitive market and this could be a big selling point. When the isp wars were going strong, before broadband put everyone under the thumb of monopolists and also before gmail, spam filtering was a serious competative advantage. Why can’t phone companies take an RBL like approach? If your VoIP service garners too ma…
At a technical level, spam filtering relies heavily on analyzing email text. Doing similar analysis on voice calls is way harder. Also, there's UI issues. You can redirect suspected spam emails to a folder the user can inspect for false positives. What do you do with a call that hits the robocall filter?