Source note · Call transfer semantics REFER and Replaces
Where a Replaces header field matches an active dialog the user agent must verify that the initiator of the new INVITE is authorised to replace it; RFC 3891 names authentication equivalent to the replaced user as sufficient, and says a user agent should treat a replacement as authorised where the request carries a Referred-By header corresponding to the user being replaced.
Checked 2026-09-16
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- Replaces
- Deployment
- not restricted
- Region
- not restricted
- Release range
- Standards Track
- Checked
- 2026-09-16
Sources
- RFC 3891 — The Session Initiation Protocol (SIP) "Replaces" Header — IETF / RFC Editor · tier 1 standards and regulators · RFC 3891 section 3, active dialog paragraphs
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-replaces-authorisation-and-referred-by. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-replaces-authorisation-and-referred-by
BibTeX
@misc{warmtransfer-claim-xfersem-replaces-authorisation-and-referred-by,
title = {Call transfer semantics REFER and Replaces: source note xfersem-replaces-authorisation-and-referred-by},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-replaces-authorisation-and-referred-by},
note = {Source note xfersem-replaces-authorisation-and-referred-by, checked 2026-09-16}
}