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NNI Task Force Introduction

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Important IP-NNI Task Force Announcement:

FCC Releases Second Report and Order in the Matter of the Call Authentication Trust Anchor (WC Docket No. 17-97) – Follows TRACED ACT Signed Into Law and the U.S. Federal Communications Commission Mandate of Adoption of STIR/SHAKEN Call Authentication Framework developed by the SIP Forum/ATIS NNI Task Force.

With the signing into law of the “Pallone-Thune Telephone Robocall Abuse Criminal Enforcement and Deterrence Act”, or the “TRACED Act” (S.151), by President Trump on December 30, 2019, there was new urgency surrounding the deployment of STIR/SHAKEN within the telecommunications industry.

On March 31, 2020, the United States Federal Communications Commission adopted new rules requiring implementation of caller ID authentication using “STIR/SHAKEN.” These rules will further the FCC’s efforts to protect consumers against malicious caller ID “spoofing,” which is often used during robocall scam campaigns to trick consumers into answering their phones.

Most recently, on October 1, 2020, the FCC released the Second Report and Order in the Matter of the Call Authentication Trust Anchor (WC Docket No. 17-97), and with this release, there are a host of new issues for the industry at large to consider.

The TRACED Act authorizes the Federal Communications Commission (FCC) to issue additional civil penalties on individuals who intentionally violate restrictions on the use of automated telephone equipment (i.e., illegal robocalls and spoofing); and directs the FCC to require voice service providers to offer call authentication technologies (i.e., STIR/SHAKEN) to consumers.

About the SIP Forum/ATIS NNI Task Force

The global communications industry is currently in the midst of an important transition from the legacy PSTN (Public Switched Telephone Network) infrastructure to a newer, more advanced SIP (Session Initiation Protocol) and IP-based infrastructure. Today, many advanced services cannot reliably work end-to-end because the interconnection between service providers often still occurs via the PSTN’s TDM-based (Time Division Multiplexing) facilities.

Although IP-based SIP interconnection between service providers is increasingly common, each agreement must be negotiated and engineered on a case-by-case basis, leading to duplication of effort. Typically, equipment, such as Session Border Controllers, is used to “normalize” the protocol at the edge of each network to ensure the interconnection will work. The overall effect is to significantly increase the operational and capital cost of SIP/IP-based interconnection. In addition, there is no commonly-agreed methodology on how to translate phone numbers for routing data for SIP-IP interconnection.

The Alliance for Telecommunications Solutions (ATIS) and the SIP Forum formed a Joint Network-to-Network Interface Task Force to fully specify an IP communications network-to-network interface between North American service providers. The Joint Task Force will enable the goal, identified in the United States National Broadband Plan, of ensuring all service interconnection between providers occur at the Internet Protocol (IP) level. By enabling ubiquitous IP-based interconnection, the Task Force supports wide-scale availability of IP-based voice services, and for laying the groundwork for ubiquitous advanced real-time communications such as high-definition voice, point-to-point video calling, and multimedia text across wireless, wireline and cable providers.

The SHAKEN Call Authentication Framework

To address unwanted and illegal Robocalls, ATIS and the SIP Forum have been working to develop standards to verify and authenticate caller identification for calls carried over an Internet Protocol (IP) network using the Session Initiation Protocol (SIP). The ATIS and SIP Forum work consists of a three-phase approach to solving the issue of caller identification, using a digital certificate scheme to “verify and authenticate caller identification for calls carried over an Internet Protocol (IP) network.”

Phase 1 (completed) consists of the development of the SHAKEN framework, based on the protocols developed by the IETF’s STIR working group (the STIR framework), and describes the operations necessary for making an authenticated telephone call using the SHAKEN framework.

Phase 2 (completed) consists of the development of a “Governance Model and Certificate Management for the Trust Anchor,” describing the way in which entities will be granted the trust necessary to vouch for call authenticity, and the organizational structures needed to manage this process. Specifically, this work introduces a governance model and defines X.509 certificate management procedures. Certificate management provides mechanisms for validation of a certificate and verification of the associated digital signature, allowing for the identification of illegitimate use of national telecommunications infrastructure.

Phase 3 consists of the development of a “Call Validation Display Framework” that will recommend how to display SHAKEN/STIR information to consumers. Phase 3 is still being developed by ATIS and the SIP Forum.


How to Join the Effort

Participation in the ATIS/SIP Forum Joint Task Force is currently open to ATIS and/or SIP Forum members.

To join the effort, you must already be an Individual “Participant” Member of the SIP Forum. This membership is completely FREE.

If you are not yet a Participant Member, please register. (Note: This link will take you to a quick and easy online form).

Once you are registered, please visit the NNI Task Group Charter page.

At the top of the charter page, you will find a link to subscribe to the NNI TF Mailing List.


SHAKEN and Other NNI Task Force Approved Publications

The following ratified publications produced by the NNI Task Force are available for download.

Please note that you must be a registered SIP Forum Participant Member and logged into the website in order to access these documents!

To register as a new SIP Forum Participant Member, click HERE.

  1. Signature-based Handling of Asserted information using toKENs (SHAKEN). This is the PDF version of the ratified NNI Task Force “SHAKEN” document. Signature-based Handling of Asserted information using toKENs (SHAKEN) is an industry framework for managing the deployment of Secure Telephone Identity (STI) technologies with the purpose of providing end-to-end cryptographic authentication and verification of the telephone identity and other information in an IP-based service provider voice network. This specification defines the framework for telephone service providers to create signatures in SIP and validate initiators of signatures. It defines the various classes of signers and how the verification of a signature can be used towards the mitigation and identification of illegitimate use of national telecommunications infrastructure and to protect its users.
  2. ATIS Standard on Toll-Free Numbers in the SHAKEN Framework (ATIS-1000093). This document is intended to cover calls using Toll-Free Numbers (TFNs) within the SHAKEN Framework. This addresses calls where the calling party number displayed in the Caller ID is a TFN. This document considers scenarios involving the calling party’s use of the TFN in order to enable them to attain full attestation for the TFN.
  3. Signature-based Handling of Asserted Information using ToKENS (SHAKEN): Delegate Certificates (ATIS-1000092). The base SHAKEN framework enables a SHAKEN-authorized VoIP Service Provider to deliver a cryptographically protected assertion (the ”attestation” value) to a terminating service provider that under specified conditions indicates the calling user is authorized to use the calling telephone number. This specification extends the base SHAKEN framework to enable SHAKEN-authorized TN Service Providers to issue delegate certificates defined in this document to their non-SHAKEN-authorized customers that allows the customer to prove it possesses an assignment or delegation of a calling TN to a SHAKEN originating service provider that is not also the TN Service Provider. This is one possible method for an originating service provider to determine that its customer’s call is entitled to full attestation for certain enterprise or legitimate call spoofing scenarios where the originating service provider does not have a direct association with the calling entity and/or the calling TN.
  4. Joint ATIS/SIP Forum Standard – Signature-Based Handling of Asserted Information Using Tokens (SHAKEN): Governance Model and Certificate Management (ATIS-1000080.v.003). This is the PDF version of the updated ratified standard. This specification expands the SHAKEN framework, introducing a governance model and defining X.509 certificate management procedures. Certificate management provides mechanisms for validation of a certificate and verification of the associated digital signature, allowing for the identification of illegitimate use of national telecommunications infrastructure. v.003 published on 2020-09-08.
  5. Signature-based Handling of Asserted information using toKENs (SHAKEN): SHAKEN Support of “div” PASSporT (ATIS-1000085.v002). The base SHAKEN specification provides replay-detection mechanisms to identify cases where a malicious entity attempts to masquerade as another user by replaying parts of a legitimate INVITE request. However, these mechanisms don’t cover cases where the INVITE is replayed within the short time freshness window. This technical report describes how the mechanisms defined by draft-ietf-stir-passport-divert [Ref 4] can be integrated within the SHAKEN framework to close this replay attack window. Published 2020-10-02.
  6. Mechanism for International Signature-based Handling of Asserted information using toKENs (SHAKEN) (ATIS-1000091). This document provides telephone service providers with a framework and guidance on how to use Secure Telephone Identity (STI) technologies on IP-based service provider voice networks (also to be referred to as Voice over Internet Protocol [VoIP] networks) in scenarios where a call originates in one country and terminates in a different country. ATIS-1000087, Mechanism for Initial Cross-Border Signature-based Handling of Asserted information using toKENs (SHAKEN), provides an initial mechanism for cross-border SHAKEN calls, but it recognizes that it is only the first step, and that a more general approach is required to accommodate the general cases of international SHAKEN calls. Published 2020-07-16.
  7. Study of Full Attestation Alternatives for Enterprises and Business Entities with Multi-Homing and Other Arrangements (ATIS-1000089). This Technical Report describes use cases where a Signature-based Handling of Asserted information using toKENs (SHAKEN) Originating Service Provider (OSP) may not have complete locally available information to establish a verified association between a calling telephone number (calling TN) and its direct Customer, as the basis for assigning a “full attestation” value to particular calls. In addition, this report summarizes a few different mechanisms: Delegated Certificates, Extended Validation (EV) Certificates with TN Letter of Authorization (TNLoA), and Central TN Database, that have been proposed to provide the OSP with additional information regarding the entity placing a call and the telephone numbers that entity has a valid association with in order to support the OSP marking the call with the highest attestation level. All three approaches are considered viable; however, they do present different tradeoffs in terms of complexity, cost to service providers and enterprises, and the assumptions around the relationship between service providers, their customers, and other entities in the SHAKEN and voice network ecosystems. It is difficult to predict how these tradeoffs will influence industry acceptance of one solution over another, and it is likely that the “best” solution will vary based on the deployment use case. Published 2020-06-22.
  8. A Framework for SHAKEN Attestation and Origination Identifier (ATIS-1000088). This technical report provides a framework for SHAKEN (ATIS-1000074-E, [Ref. 1]) attestation and granularity of the Origination Identifier. Published 2020-02-13.
  9. Mechanism for Initial Cross-Border Signature-based Handling of Asserted information using toKENs (SHAKEN) (ATIS-1000087). This document provides telephone service providers with a framework and guidance on how to use Secure Telephone Identity (STI) technologies on IP-based service provider voice networks (also to be referred to as Voice over Internet Protocol [VoIP] networks) in scenarios where a call originates in one country and terminates in a different country. The primary focus of this document is to detail how the trust environment created by Signaturebased Handling of Asserted information using toKENs (SHAKEN) in a single country can be extended to include other countries. This document does not require any changes to the existing SHAKEN specifications but does identify new interfaces and functions to exchange information between countries.
  10. Technical Report on a Framework for Display of Verified Caller ID. The Technical Report on a Framework for Display of Verified Caller ID provides a framework for signaling verified Caller ID information from the network to a User Equipment (UE), and displaying the information on the UE in a uniform manner, independent of technology. The goal is to produce display guidelines that help meet the goals of regulators and consumer protection agencies for empowering consumers with simple and effective information on the displayed Caller ID. This will help consumers know if a call is from who it says it is from so they can make an informed decision on whether to answer.
  11. Technical Report on SHAKEN API for a Centralized Signing and Signature Validation Server. The Technical Report on SHAKEN API for a Centralized Signing and Signature Validation Server provides additional detail on one possible implementation of the SHAKEN specification in service provider networks. It defines a RESTful interface (API) that can be used in the SHAKEN framework to interface with a centralized server to sign and verify telephony identity for multiple nodes within a network. Implementing SHAKEN authentication and verification functions in a centralized server that can be accessed via an API supports cloud-based implementations and is designed to enable a more cost-effective network deployment.
  12. Technical Report on Operational and Management Considerations for SHAKEN STI Certification Authorities and Policy Administrators (ATIS-1000084.v002). This document provides operational and management considerations for the Certification Authorities with the SHAKEN Governance Model and Certificate Management framework. It introduces considerations for the STI Policy Administrator in managing the list of valid STI CAs and authorized Service Providers, as well as general operational and policy considerations for PKI. This document introduces those aspects which are unique to the SHAKEN use of PKI. Updated v.002 document published 2020-2020-09-02.
  13. Joint ATIS/SIP FORUM Technical Report – IP NNI Profile
    This is the ratified version of the IP NNI Profile Specification, published by the joint ATIS/SIP Forum NNI Task Force. The IP-NNI Profile Specification defines a reference architecture and specifications for both the protocol and media as it appears “on-the-wire” at interconnect points. The specifications reference commonly used IETF, 3GPP, and other related industry specifications and identify protocol extensions and capability information needed for all-IP telephony peering.
  14. Joint ATIS/SIP Forum Technical Report – IP Interconnection Routing
    This is the ratified version of the IP Interconnection Routing Report, published by the joint ATIS/SIP Forum NNI Task Force. The IP-NNI Routing Technical Report documents mechanisms for identifying the preferred IP interconnection point for a given TN. This report presents multiple views of current IP interconnection mechanisms based on aggregate PSTN constructs, interim solutions based on all-IP routing using a per-TN registry, and a consideration of hybrid approaches across both mechanisms during the transition to all-IP.

STIR/SHAKEN Presentations and Webinars

For a listing of webinar recordings that are free to view, please visit the June 2020 STIR/SHAKEN VIRTUAL SUMMIT agenda webpage.

Also find below a sampling of presentations about STIR/SHAKEN-related topics from past SIPNOC conferences and other events that are available for download:

  1. Overview of the STIR / SHAKEN Framework and Current NNI Task Force Milestones. This presentation was given by Martin Dolly, AT&T, and Co-Chair of the NNI Task Force during SIPNOC 2019.
  2. Overview and Update of the Secure Telephone Identity Governance Authority. This presentation was given by Presented by Linda Vandeloop, AVP External Affairs/Regulatory, AT&T and Chair, STI Governance Authority, during SIPNOC 2019.
  3. Operational Aspects of the STI-PA Policy Administrator including lessons learned on Certificate Management.. This presentation was given by Mary Barnes, SIP Forum, during SIPNOC 2019.
  4. Call Validation Display Framework: Challenges and Opportunities. What Do We Show to the Consumer?. This presentation was given by Richard Shockey SIP Forum Chairman, during SIPNOC 2018.
  5. Considerations Surrounding Enterprise Delegated Certificates. This presentation was given by Chris Wendt, Principle Architect, IP Communications and Services, Comcast, Director, SIP Forum, and Co-Chair of the NNI Task Force, during SIPNOC 2019.
  6. Introduction to Digital Signatures, Certificates and PKI.. This presentation was given by Russ Housley, Principal, Vigilsec, and Co-Chair of the IETF STIR WG. STIR / SHAKEN Working Group during SIPNOC 2018.
  7. SHAKEN and STIRed: Thoughts on the Current State of: Anti Spoofing / Caller Validation / Robocall Mitigation / Call Validation Display. This presentation was given by Richard Shockey during the Ribbon Communications STIR-SHAKEN Summit, March 2019.
  8. Full Attestation Alternatives for Enterprises and Business Entities with Multi-Homing and Other Arrangements. Presented by Gary Richenaker, Principal Solutions Architect, iconectiv during SIPNOC 2019.

For additional presentations, please visit the archived SIPNOC 2019 agenda webpage. Please note that the titles of each agenda item are hyperlinked to the associated presentation.


FCC and Other Regulatory Actions Regarding Robocalls and Caller ID Spoofing

Robocalls and telemarketing calls are currently the number one source of consumer complaints at the FCC.What was once a nuisance has become a plague to U.S consumers receiving billions of robocalls a month.

The FCC has been encouraging service providers to offer call blocking solutions that give customers greater control over the types of calls they receive. Call blocking is one part of the robocall solution. Another part is identifying the bad actors who use robocalls to take advantage of unsuspecting consumers by using numbers assigned to others (spoofing). They use cheap and accessible technologies to spoof their caller identity and scam victims with threats from the IRS, offers of loans, or free travel. The Strike Force is committed to protecting customers, but these disguised calls have put investigators and enforcers at a disadvantage.

Although several providers and third parties offer call blocking and caller identification verification products, there is no ubiquitous solution that spans wireline and wireless communication networks. The industry has been called to action by the Robocall Strike Force to collaborate on creative solutions to this ever changing problem.

The mission of the cross industry Strike Force is to accelerate the development and adoption of new tools and solutions to abate the proliferation of illegal and unwanted robocalls, to promote greater consumer control over the calls they wish to receive, and to make recommendations to the FCC on the role government can play in this battle.

The following information related to the FCC’s Robocall Strike Force and other FCC and FTC regulatory, and U.S. legislative actions include:


SHAKEN in the News


For More Information

For more information about the NNI Task Force, and the work in progress, please visit the ATIS/SIP Forum NNI Task Force Charter.

You can also access NNI Task Group announcements as follows: