Protections the FCC has adopted that shield voice providers from liability when they block calls in good faith using reasonable analytics or specified criteria.
Blocking calls has traditionally been risky for carriers, because call completion obligations discourage interfering with traffic. To encourage robocall blocking, the FCC created safe harbors that protect providers from liability under its rules when they block in specified circumstances. They were adopted in stages as the FCC expanded both the expectations on providers and the tools available to them.
The main safe harbor covers blocking based on reasonable analytics that incorporate caller ID authentication information, provided it is done in good faith and managed with reasonable care. Another covers blocking traffic from bad-actor upstream providers that fail to take effective action against illegal calls after being notified. The safe harbors come with conditions, including offering a way for callers to dispute erroneous blocking and providing notice when calls are blocked.
The safe harbors are distinct from the TCPA safe harbor available to callers who consult the FCC's reassigned numbers database, which addresses a different problem. Providers should read the conditions of each safe harbor closely, because protection depends on meeting all of them, not just on the decision to block.
Why it matters to carriers
If you block or filter traffic, the safe harbors are what make that defensible. Staying inside them means documenting your analytics, offering a redress process, and returning the right SIP response codes when calls are blocked. Blocking outside those boundaries can expose you to complaints and call completion concerns.