scope:

This report provides an overview of the activities designed to produce and implement measures to mitigate both the scourge of illicit robocalling and the falsification of originating party identities that support it. This report begins by defining the real problems to be solved: specifically, how this impacts the choice and prioritization of mitigation solutions.

The report provides a single reference source that describes the various mitigation activities and points to more detailed sources of information about each one. It also discusses how these various techniques are used in combination to optimize mitigation, and how they impact and are impacted by the supporting regulatory and enforcement activities.

This report also examines parallel activities to mitigate illicit messaging spam with characteristics common with robocalling, such as Short Message Service (SMS) spamming, which shares a common address space.

Illegal spoofing and robocalling originate in many other regions rather than only North America, so this report also discusses global activities.

Finally, this report outlines opportunities for additional work by ATIS and other groups to enhance the current work on illicit robocalling mitigation. It also examines how this work can create opportunities for further commercial investment in technology to re-establish trust in the telecommunications network.

Note that in the U.S., illicit robocalling mitigation efforts have focused on helping recipients of these bad calls. This report reflects that emphasis. However, in other regions, the impact of similar illicit activity, notably ID spoofing, has also been felt by network operators because it directly impacts their revenues.⁸ This report does not explicitly address that issue.

The major issue the industry confronts is the loss of consumer trust in telephony networks to deliver useful voice and SMS services. Because illicit callers spoof caller ID, many customers cannot distinguish between legitimate calls and those from illegal robocallers.

For this trust to be restored, the telecommunications industry and its regulators need access to tools that will eliminate or substantially reduce delivery of such calls or, at very least, warn recipients that a call may have bad intent.

⁸ I3 Forum, Technical Report: Calling Line Identification (CLI) Spoofing, Release 1.0, October 2020,