Source note · Call transfer semantics REFER and Replaces
A transfer that protects the Transfer Target's identity reverses the roles so that the original Target transfers the Transferee, which means the Transferee experiences a new inbound call from the Target; RFC 5589 warns that unless the Transferee can reliably associate that call with the one it already has it may have to alert on another appearance or return a Busy Here that prevents the transfer.
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 7.2 Protecting Transfer Target
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-target-protecting-transfer-reverses-the-roles. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-target-protecting-transfer-reverses-the-roles
BibTeX
@misc{warmtransfer-claim-xfersem-target-protecting-transfer-reverses-the-roles,
title = {Call transfer semantics REFER and Replaces: source note xfersem-target-protecting-transfer-reverses-the-roles},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-target-protecting-transfer-reverses-the-roles},
note = {Source note xfersem-target-protecting-transfer-reverses-the-roles, checked 2026-09-16}
}