In the SIP-to-ISUP direction RFC 3398 maps SIP 503 Service Unavailable to ISUP cause 41 (temporary failure).

Checked 2026-09-24

Vendor
IETF
Product
RFC 3398
Subsystem
status-to-cause mapping
Deployment
any
Region
not restricted
Release range
RFC 3398
Checked
2026-09-24

Sources

Cite this note

APA

WarmTransfer. (2026, September 24). PRI and TDM gateway interworking: source note legacy-pri-tdm-sip503-to-cause41. WarmTransfer. https://warmtransfer.net/knowledge/claims/legacy-pri-tdm-sip503-to-cause41

BibTeX

@misc{warmtransfer-claim-legacy-pri-tdm-sip503-to-cause41,
  title  = {PRI and TDM gateway interworking: source note legacy-pri-tdm-sip503-to-cause41},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/legacy-pri-tdm-sip503-to-cause41},
  note   = {Source note legacy-pri-tdm-sip503-to-cause41, checked 2026-09-24}
}

Read in context