Source note · SIP 503 and trunk out-of-service failures
RFC 5390 notes that the cases in which a server should send 503 are ambiguous and that implementations send 503 for many reasons, only some of which are actual overload.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- response codes
- Deployment
- any
- Region
- not restricted
- Release range
- 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 5.4 Ambiguous Usages
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-503-ambiguous. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-503-ambiguous
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-503-ambiguous,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-503-ambiguous},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-503-ambiguous},
note = {Source note sip-503-trunk-failures-503-ambiguous, checked 2026-09-25}
}