Clients should prepare now for compliance

Carriers that are blocking suspected illegal robocalls from entering their networks and reaching customers must begin sending response codes to the caller beginning January 1, 2022. The FCC’s Fourth Report and Order – Advanced Methods to Target and Eliminate Unlawful Robocalls requires any terminating provider that blocks calls, either itself or through a third-party blocking service, to immediately return an appropriate response code to the origination point of the call. All voice service providers in the call path must also transmit the response code.

The required response codes will vary based on the blocking carrier’s type of network. The appropriate response codes are:

  • Session Initiation Protocol (SIP) code 607 or 608 for a call terminating on an IP network
  • ISDN User Part (ISUP) code 21 with the cause location “user” for a call terminating on a non-IP network
  • When a code transmits from an IP network to a non-IP network, SIP codes 607 and 608 must map to ISUP code 21
  • When a code transmits from a non-IP network to an IP network, ISUP code 21 must map to SIP code 603, 607, or 608 where the cause location is “user.”

All voice service providers must make the necessary software upgrades and configuration changes to ensure that these codes translate properly when a call moves between TDM and IP-based networks.

Unless the FCC issues waivers for small carriers or delays the effective date, the requirement begins January 1, 2022. Contact Bridget Alexander White at 301-459-7590 if you have any questions regarding this requirement or any other robocall mitigation efforts.