Source note · Call transfer semantics REFER and Replaces

RFC 7647 requires that a user agent wishing to identify an existing dialog, such as for call transfer as defined in RFC 5589, uses the Target-Dialog extension of RFC 4538, and that user agents accepting REFER are able to process that extension in requests they receive.

Checked 2026-09-16

A user agent wishing to identify an existing dialog (such as for call transfer as defined in [ RFC5589 ]) MUST use the "Target-Dialog" extension defined in [ RFC4538 ] to do so, and user agents accepting REFER MUST be able to process that extension in requests they receive.

Vendor: IETF
Product: Session Initiation Protocol
Subsystem: REFER
Deployment: not restricted
Region: not restricted
Release range: Updates RFC 3515
Checked: 2026-09-16

Sources

RFC 7647 — Clarifications for the Use of REFER with RFC 6665 — IETF / RFC Editor · tier 1 standards and regulators · RFC 7647 section 4 Dialog Reuse Is Prohibited, final paragraphs

Cite this note

APA

WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-target-dialog-is-mandatory-for-transfer. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-target-dialog-is-mandatory-for-transfer

BibTeX

@misc{warmtransfer-claim-xfersem-target-dialog-is-mandatory-for-transfer,
  title  = {Call transfer semantics REFER and Replaces: source note xfersem-target-dialog-is-mandatory-for-transfer},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/xfersem-target-dialog-is-mandatory-for-transfer},
  note   = {Source note xfersem-target-dialog-is-mandatory-for-transfer, checked 2026-09-16}
}

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