Source note · Call transfer semantics REFER and Replaces
RFC 3515 gives a minimal but complete set of 4 NOTIFY bodies: SIP/2.0 100 Trying while the subscription is pending, SIP/2.0 200 OK if the reference succeeded, SIP/2.0 503 Service Unavailable if it failed, and SIP/2.0 603 Declined where the REFER was accepted before approval could be obtained and approval was then denied.
Checked 2026-09-16
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- REFER
- Deployment
- not restricted
- Region
- not restricted
- Release range
- Standards Track
- Checked
- 2026-09-16
Sources
- RFC 3515 — The Session Initiation Protocol (SIP) Refer Method — IETF / RFC Editor · tier 1 standards and regulators · RFC 3515 section 2.4.5
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-refer-minimal-notify-bodies. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-refer-minimal-notify-bodies
BibTeX
@misc{warmtransfer-claim-xfersem-refer-minimal-notify-bodies,
title = {Call transfer semantics REFER and Replaces: source note xfersem-refer-minimal-notify-bodies},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-refer-minimal-notify-bodies},
note = {Source note xfersem-refer-minimal-notify-bodies, checked 2026-09-16}
}