Source note · Call transfer semantics REFER and Replaces
RFC 5589 says the Require replaces header field should be used in the triggered INVITE of an attended transfer, to prevent a user agent that does not support Replaces from ignoring it and answering the INVITE without a dialog match.
Checked 2026-09-16
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- Attended 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 7.3, paragraph 3
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-require-replaces-on-the-triggered-invite. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-require-replaces-on-the-triggered-invite
BibTeX
@misc{warmtransfer-claim-xfersem-require-replaces-on-the-triggered-invite,
title = {Call transfer semantics REFER and Replaces: source note xfersem-require-replaces-on-the-triggered-invite},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-require-replaces-on-the-triggered-invite},
note = {Source note xfersem-require-replaces-on-the-triggered-invite, checked 2026-09-16}
}