Source note · SIP 503 and trunk out-of-service failures
RFC 3261 allows proxies to refuse the connection or drop the request instead of responding with 503.
Checked 2026-09-25
Proxies MAY refuse the connection or drop the request instead of responding with 503 (Service Unavailable).
- Vendor
- IETF
- Product
- SIP
- Subsystem
- proxy overload behaviour
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3261 as quoted 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 (quotation of RFC 3261)
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-proxy-may-drop. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-proxy-may-drop
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-proxy-may-drop,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-proxy-may-drop},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-proxy-may-drop},
note = {Source note sip-503-trunk-failures-proxy-may-drop, checked 2026-09-25}
}