RFC 3398 maps ISUP cause 18 (no user responding) received from the PSTN to SIP 408 Request Timeout.
Checked 2026-10-02
18 no user responding 408 Request Timeout
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- SIP-ISUP interworking
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3398, current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- RFC 3398: Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping — IETF / RFC Editor · tier 1 standards and regulators · Section 7.2.4.1 ISUP cause to SIP status mapping table
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-rfc3398-isup-18-to-408. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-rfc3398-isup-18-to-408
BibTeX
@misc{warmtransfer-claim-sip-408-timeout-troubleshooting-rfc3398-isup-18-to-408,
title = {Troubleshooting SIP 408 Request Timeout and calls that get no response: source note sip-408-timeout-troubleshooting-rfc3398-isup-18-to-408},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-rfc3398-isup-18-to-408},
note = {Source note sip-408-timeout-troubleshooting-rfc3398-isup-18-to-408, checked 2026-10-02}
}