RFC 4321 notes that a SIP proxy cannot reliably distinguish an element that has failed from one that is merely slow to respond, which complicates blacklisting of unresponsive next hops.
Checked 2026-10-02
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- SIP proxy
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 4321, current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- RFC 4321: Problems Identified Associated with the Session Initiation Protocol's (SIP) Non-INVITE Transaction — IETF / RFC Editor · tier 1 standards and regulators · Section 1.3
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting SIP 408 Request Timeout and calls that get no response: source note sip-408-timeout-troubleshooting-rfc4321-dead-vs-slow. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-rfc4321-dead-vs-slow
BibTeX
@misc{warmtransfer-claim-sip-408-timeout-troubleshooting-rfc4321-dead-vs-slow,
title = {Troubleshooting SIP 408 Request Timeout and calls that get no response: source note sip-408-timeout-troubleshooting-rfc4321-dead-vs-slow},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-rfc4321-dead-vs-slow},
note = {Source note sip-408-timeout-troubleshooting-rfc4321-dead-vs-slow, checked 2026-10-02}
}