Source note · SIP call forwarding and routing loops
History-Info entries can carry a Reason header with the SIP response code that caused the retargeting, for example 302 for unconditional forwarding, 486 for busy, 408 for timeout or 480 for temporarily unavailable.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- History-Info
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 7044 onward
- Checked
- 2026-09-25
Sources
- RFC 7044: An Extension to the Session Initiation Protocol (SIP) for Request History Information — IETF / RFC Editor · tier 1 standards and regulators · Section 10.2 (Reason header in hi-entries)
Cite this note
APA
WarmTransfer. (2026, September 25). SIP call forwarding and routing loops: source note sip-forwarding-loops-history-info-reason. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-history-info-reason
BibTeX
@misc{warmtransfer-claim-sip-forwarding-loops-history-info-reason,
title = {SIP call forwarding and routing loops: source note sip-forwarding-loops-history-info-reason},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-history-info-reason},
note = {Source note sip-forwarding-loops-history-info-reason, checked 2026-09-25}
}