Source note · SIP 503 and trunk out-of-service failures
Using 503 for overload can make traffic oscillate and shift between SIP servers, worsening the overload.
Checked 2026-09-25
In fact, the use of the 503 (Service Unavailable) response code may cause traffic to oscillate and shift between SIP servers, thereby worsening an overload condition.
- 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 · Section 1 Introduction
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-503-oscillation. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-503-oscillation
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-503-oscillation,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-503-oscillation},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-503-oscillation},
note = {Source note sip-503-trunk-failures-503-oscillation, checked 2026-09-25}
}