Final rule · 2025-04811

Advanced Methods To Target and Eliminate Unlawful Robocalls

In this document, the Federal Communications Commission (Commission) modifies its existing call blocking rules. Specifically, the Commission requires all domestic voice service providers to block based on a reasonable do-not-originate (DNO) list. Second, it requires voice service providers to return Session Initiation Protocol (SIP) code 603+ when calls are blocked based on reasonable analytics.