Source note · Call transfer semantics REFER and Replaces

Terminating a refer subscription, either by unsubscribing or by rejecting a NOTIFY, is not an indication that the referenced request should be withdrawn, and RFC 3515 states that an agent acting on a REFER should not issue a CANCEL to the referenced request because the referring agent ended its subscription before that request completed.

Checked 2026-09-16

Terminating a subscription, either by explicitly unsubscribing or rejecting NOTIFY, is not an indication that the referenced request should be withdrawn or abandoned.

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

Sources

RFC 3515 — The Session Initiation Protocol (SIP) Refer Method — IETF / RFC Editor · tier 1 standards and regulators · RFC 3515 section 2.4.4

Cite this note

APA

WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-unsubscribing-does-not-cancel-the-transfer. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-unsubscribing-does-not-cancel-the-transfer

BibTeX

@misc{warmtransfer-claim-xfersem-unsubscribing-does-not-cancel-the-transfer,
  title  = {Call transfer semantics REFER and Replaces: source note xfersem-unsubscribing-does-not-cancel-the-transfer},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/xfersem-unsubscribing-does-not-cancel-the-transfer},
  note   = {Source note xfersem-unsubscribing-does-not-cancel-the-transfer, checked 2026-09-16}
}

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