Overview
As part of its work to mitigate illegal robocalling, ATIS is launching a task force to investigate non-IP call authentication. Service Providers that operate non-IP (i.e., TDM) networks as well as others that may have an interest in non-IP call authentication are encouraged to participate.
Background
ATIS has been at the forefront of efforts to develop call authentication standards and has been actively working with the SIP Forum through the joint ATIS-SIP Forum IP Network-to-Network Interface (IP-NNI) Task Force on to develop the SHAKEN series of specifications. This work has appropriately focused on IP-to-IP call authentication. However, the passage of the TRACED Act and adoption by the Federal Communications Commission (FCC) of its March 2020 order and rulemaking highlighted a need to further examine TDM call authentication.
The FCC’s rulemaking, for example, would establish deadlines for the implementation of call authentication in TDM networks. Additional time would be provided for service providers that undertake “reasonable efforts,” which the FCC indicates would be satisfied if a voice service provider can demonstrate that it is participating as a member of a working group or consortium that is working to develop a TDM solution.
ATIS recently published three documents from its Non-IP Call Authentication Task Force (NIPCA-TF) to advance the industry’s illegal robocalling mitigation goals in non-IP (i.e., TDM) networks. The following describes these standards and provides the context of the overall work of the NIPCA-TF.
The Technical Report, ATIS-1000106, Viability of Non-IP Call Authentication Standards, studies the viability of operationalizing solutions where various non-IP call authentication standards coexist and integrate with the SHAKEN solution in IP networks. This standard considers some of the fundamental concepts of Non-IP Call Authentication Standards in its viability analysis. This standard is under revision.
The NIPCA-TF also produced a standard, ATIS-1000105, Signature-based Handling of Asserted information using Tokens (SHAKEN): Out-of-Band PASSporT Transmission Between Service Providers that Interconnect using TDM, that uses a framework enabling an authorized Voice over Internet Protocol (VoIP) service provider to deliver a cryptographically signed PASSporT(s) are exchanged out-of-band, that is, separate from the telephone network signaling. This enable the assertion that the calling user is authorized to use the calling telephone number to a called user via Session Initiation Protocol (SIP) signaling that the calling user is authorized to use the calling telephone number. This specification extends the SHAKEN framework, governance model, and certificate management to enable service providers using Time Division Multi-plexing (TDM) signaling and/or switches to participate in the SHAKEN ecosystem without placing any new requirements on authorized SHAKEN service providers. It describes a mechanism where PASSporTs are exchanged between each pair of service providers that interconnect using TDM and provides several calling scenario examples.
Both ATIS-1000105 and previously published ATIS-1000096 solve for the same problem of ensuring STIR/SHAKEN PASSporTs are not lost where a TDM network is within the call path. ATIS-1000105 uses a hop-by-hop approach where bilateral agreement specify the call placement service (“CPS”) arrangement between service providers for the transmission of STIR SHAKEN PASSporTs while ATIS-1000097 relies upon a broadcast model where PASSporT information is broadcasted to all participating CPS providers.
Also, revised was the Technical Report, ATIS-1000097.v003, Alternatives for Call Authentication for Non-IP Traffic. This deliverable identifies non-IP call authentication scenarios and provides a framework to evaluate potential approaches that could provide call authentication even when the call is not SIP end-to-end (non-IP). A SHAKEN-authorized VoIP Service Provider through the SHAKEN framework, governance model, and certificate management are permitted to deliver a cryptographically protected assertion that the calling user is authorized to use the calling telephone number to a called user via SIP signaling.
ATIS-1000095 is a previously published ATIS standard that provides a methodology for the transmission of STIR/SHAKEN attestation across a TDM network through the repurposing of an SS7 parameter. Similarly, the standard also describes the repurposing of the SS7 protocol to transmit the STIR/SHAKEN PASSporT. The standard does not specify the potential interoperability concerns associated with the SS7 parameters that may already be in use.
More information
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- Join a Forefront Industry Group Addressing the Challenges of TDM Call Authentication
- Why Join?
Please contact Rich Moran, ATIS for more information about the Non-IP Call Authentication Task Force.
Learn More
Call Authentication for Non-IP Networks – TRACED Act Compliance
Watch webinar | View slides