Source note · SIP call forwarding and routing loops
RFC 3261 distinguishes a spiral from a loop: a request that returns to the same proxy with a different Request-URI (for example after call forwarding) is a spiral and is legitimate, not a loop.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- proxy loop detection
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3261 (June 2002)
- Checked
- 2026-09-25
Sources
- RFC 3261 — SIP: Session Initiation Protocol — IETF / RFC Editor · tier 1 standards and regulators · Section 16.3 Request Validation, item 4 (spiral discussion)
Cite this note
APA
WarmTransfer. (2026, September 25). SIP call forwarding and routing loops: source note sip-forwarding-loops-spiral-not-loop. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-spiral-not-loop
BibTeX
@misc{warmtransfer-claim-sip-forwarding-loops-spiral-not-loop,
title = {SIP call forwarding and routing loops: source note sip-forwarding-loops-spiral-not-loop},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-forwarding-loops-spiral-not-loop},
note = {Source note sip-forwarding-loops-spiral-not-loop, checked 2026-09-25}
}