Source note · Call transfer semantics REFER and Replaces
RFC 7647 prohibits dialog reuse for REFER: where the peer in an existing dialog has provided a Globally Routable User Agent URI as its contact, a user agent constructing a REFER that could create an implicit subscription must build it as an out-of-dialog message, so the REFER carries no tag in its To header field. The exception is a peer that is an older RFC 3515 implementation, identified by the absence of such a URI in the remote target.
Checked 2026-09-16
- 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 sections 3 and 4
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-refer-must-be-out-of-dialog-with-gruu. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-refer-must-be-out-of-dialog-with-gruu
BibTeX
@misc{warmtransfer-claim-xfersem-refer-must-be-out-of-dialog-with-gruu,
title = {Call transfer semantics REFER and Replaces: source note xfersem-refer-must-be-out-of-dialog-with-gruu},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-refer-must-be-out-of-dialog-with-gruu},
note = {Source note xfersem-refer-must-be-out-of-dialog-with-gruu, checked 2026-09-16}
}