Source note · SIP 503 and trunk out-of-service failures
RFC 3261 tells proxies not to forward 503 responses upstream, at SHOULD NOT strength.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- proxy response processing
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3261 as described in RFC 5390; current as of 2026-09-25
- Checked
- 2026-09-25
Sources
- RFC 5390: Requirements for Management of Overload in the Session Initiation Protocol — IETF / RFC Editor · tier 1 standards and regulators · Section 4
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-proxy-no-forward-503. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-proxy-no-forward-503
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-proxy-no-forward-503,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-proxy-no-forward-503},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-proxy-no-forward-503},
note = {Source note sip-503-trunk-failures-proxy-no-forward-503, checked 2026-09-25}
}