Source note · Call transfer semantics REFER and Replaces
RFC 5589 describes a race in which the Transferor abandons a consultation and turns it into a blind transfer: the Transfer Target on a gateway answers just after receiving the CANCEL, so when the triggered INVITE arrives the Transferee reaches a busy response or the target's voicemail because the handset is off hook, and the recommended behaviour is the semi-attended flow of section 7.6.
Checked 2026-09-16
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- Gateway 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 11.2 Consultative Turned Blind Gateway Glare
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-consultative-turned-blind-glare. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-consultative-turned-blind-glare
BibTeX
@misc{warmtransfer-claim-xfersem-consultative-turned-blind-glare,
title = {Call transfer semantics REFER and Replaces: source note xfersem-consultative-turned-blind-glare},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-consultative-turned-blind-glare},
note = {Source note xfersem-consultative-turned-blind-glare, checked 2026-09-16}
}