Source note · Call transfer semantics REFER and Replaces

RFC 5589 describes blind or unattended transfer as the case where the Transferor's agent does not wish to take part in the rest of the REFER process and has no intention of assisting with recovery, and so emits a BYE to the Transferee as soon as the REFER transaction completes.

Checked 2026-09-16

If the Transferor's agent does not wish to participate in the remainder of the REFER process and has no intention of assisting with recovery from transfer failure, it could emit a BYE to the Transferee as soon as the REFER transaction completes. This flow is sometimes known as "unattended transfer" or "blind transfer".

Vendor: IETF
Product: Session Initiation Protocol
Subsystem: Basic transfer
Deployment: not restricted
Region: not restricted
Release range: BCP 149
Checked: 2026-09-16

Sources

RFC 5589 — Session Initiation Protocol (SIP) Call Control - Transfer — IETF / RFC Editor · tier 1 standards and regulators · RFC 5589 section 6, note preceding Figure 1

Cite this note

APA

WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-blind-transfer-is-basic-plus-an-early-bye. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-blind-transfer-is-basic-plus-an-early-bye

BibTeX

@misc{warmtransfer-claim-xfersem-blind-transfer-is-basic-plus-an-early-bye,
  title  = {Call transfer semantics REFER and Replaces: source note xfersem-blind-transfer-is-basic-plus-an-early-bye},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/xfersem-blind-transfer-is-basic-plus-an-early-bye},
  note   = {Source note xfersem-blind-transfer-is-basic-plus-an-early-bye, checked 2026-09-16}
}

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