Source note · SIP 503 and trunk out-of-service failures
RFC 7339 (Standards Track, September 2014) carries overload feedback hop by hop in Via header parameters oc, oc-algo, oc-validity and oc-seq; a client adds oc to the topmost Via it inserts and the server returns a value in the response's topmost Via.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- overload control
- Deployment
- any
- Region
- not restricted
- Release range
- current as of 2026-09-25
- Checked
- 2026-09-25
Sources
- RFC 7339: Session Initiation Protocol (SIP) Overload Control — IETF / RFC Editor · tier 1 standards and regulators · Sections 4.1 to 4.4 and 5.2
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-rfc7339-via-oc. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-rfc7339-via-oc
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-rfc7339-via-oc,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-rfc7339-via-oc},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-rfc7339-via-oc},
note = {Source note sip-503-trunk-failures-rfc7339-via-oc, checked 2026-09-25}
}