It's worth reading Pai's actual dissent: https://apps.fcc.gov/edocs_public/attachmatch/FCC-15-72A5.pd.... Among his reasons for dissenting is that the Commission was unwilling to "establish[] a safe harbor so that carriers could block spoofed calls from overseas without fear of liability."

All this occurs against the background of the Communications Act's common-carrier obligations, and the FCC's call-completion rules, which generally prohibit blocking calls. What the FCC did in the order you linked is to simply say "nothing in the Communications Act or our rules or orders prohibits carriers or VoIP providers from implementing call-blocking technology that can help consumers who choose to use such technology to stop unwanted robocalls."

Is that a safe harbor? No, as the next sentence clarifies, what can be blocked depends on the nature of the call: "Additionally, in the interests of public safety, we strongly encourage carriers, VoIP providers, and independent call-blocking service providers to avoid blocking autodialed or prerecorded calls from public safety entities, including PSAPs, emergency operations centers, or law enforcement agencies; blocking these calls may compromise the effectiveness of local and state emergency alerting and communications programs."

As explained in other posts here, it's hard for a carrier to tell what is a robocall. What is an "unwanted" robocall is even harder--it's a heavily-litigated issue in the TCPA context. (In fact, the rest of the order was about expanding what counts as an unwanted robocall in violation of the TCPA).

That leaves carriers between a rock and a hard place--it they block over-inclusively, businesses who think they fall into a TCPA exception could sue them for violating their common-carrier obligations. Then they get to litigate whether that business falls within the scope of the "unwanted robocalls" the FCC referred to (but did not define). Carriers have a huge incentive to not wander into that morass by offering call-blocking features.

> so that carriers could block spoofed calls from overseas without fear of liability

I don't really want my carrier deciding what calls to block. I just want them to ensure the veracity of caller ID data so that I can perform useful blocking at my end. There shouldn't be anything stopping them from removing fraudulent and unverifiable caller ID info from the calls they route my way. That leaves me free to block calls that lack caller ID info, and I'm assuming all the risks that entails.

Completely agree. For the carriers, robocall blocking is not a technical problem, it's a legal/liability one.

This makes third party call blocking products a better/easier solution for carriers to recommend as a solution.