Source note · Call transfer semantics REFER and Replaces
A REFER request must contain exactly one Refer-To header field value, and an agent responding to a REFER must return 400 Bad Request if the request contained zero or more than one.
Checked 2026-09-16
An agent responding to a REFER method MUST return a 400 (Bad Request) if the request contained zero or more than one Refer-To header field values.
- 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 sections 2.4.1 and 2.4.2
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-refer-exactly-one-refer-to. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-refer-exactly-one-refer-to
BibTeX
@misc{warmtransfer-claim-xfersem-refer-exactly-one-refer-to,
title = {Call transfer semantics REFER and Replaces: source note xfersem-refer-exactly-one-refer-to},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-refer-exactly-one-refer-to},
note = {Source note xfersem-refer-exactly-one-refer-to, checked 2026-09-16}
}