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Work item:
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Q.SSP4SIP
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Subject/title:
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Secure signalling procedures for the session initiation protocol in telecommunications networks
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Status:
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Under study
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Approval process:
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AAP
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Type of work item:
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Recommendation
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Version:
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New
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Equivalent number:
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-
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Timing:
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2027-12 (Medium priority)
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Liaison:
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ITU-T SG2, SG17, IETF, ATIS
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Supporting members:
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SomosGov (USA), USA, Luxembourg
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Summary:
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This Recommendation specifies secure signalling procedures for the Session Initiation Protocol (SIP) in telecommunications networks, defining how IETF Secure Telephone Identity Revisited (STIR) mechanisms are applied within the governance and certificate trust framework established by ITU-T Q.TSCA and ITU-T E.RAA4Q.TSCA.
Specifically, this Recommendation defines procedures for generating and verifying PASSporT objects and SIP Identity headers conveying telephone number identity and associated communications claims, including calling line identification, attestation level, rich call data, diversion information, and origination eligibility. It specifies how a CSP signs SIP signalling using STIR certificates scoped to its assigned telephone number ranges, asserting authoritative originating identity within the TSCA-CA trust hierarchy. This signing mechanism extends to support cases where a telephone number assignee that is not the assigning CSP needs to demonstrate right-to-use authority for a telephone number to a terminating CSP, enabling authenticated SIP communications to be initiated on behalf of numbers it holds the right to use.
This Recommendation also defines, as an extended capability, the use of delegated certificate mechanisms enabling a telephone number assignee that is not the assigning CSP to demonstrate right-to-use of a telephone number to a terminating network, consistent with the delegation model defined in IETF RFC 9060.
Cross-border trust anchor discovery and validation procedures are defined using the CB-TACL mechanisms of ITU-T E.RAA4Q.TSCA, ensuring globally interoperable certificate path validation while preserving Member State sovereignty in trust anchor recognition. This Recommendation does not redefine IETF STIR specifications nor replicate regional SHAKEN governance models; it provides the procedural profile for applying those mechanisms within the ITU-T Q-series trust architecture.
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Comment:
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-
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Reference(s):
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Historic references:
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Contact(s):
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| ITU-T A.5 justification(s): |
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First registration in the WP:
2026-03-18 18:19:43
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Last update:
2026-03-18 18:24:17
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