Source note · Carrier escalation evidence packages
Because several distinct ISUP causes collapse to SIP 503 under RFC 3398, an escalation that reports only the SIP status code loses the PSTN-side reason; including any Q.850 cause from a Reason header preserves it.
inferred · Checked 2026-09-24
- Vendor
- IETF
- Product
- SIP
- Subsystem
- cause mapping
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3398 and RFC 3326
- Status
- inferred
- Checked
- 2026-09-24
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 8.2.6.1 read together with RFC 3326 section 2
Cite this note
APA
WarmTransfer. (2026, September 24). Carrier escalation evidence packages: source note carrier-escalation-evidence-503-ambiguity. WarmTransfer. https://warmtransfer.net/knowledge/claims/carrier-escalation-evidence-503-ambiguity
BibTeX
@misc{warmtransfer-claim-carrier-escalation-evidence-503-ambiguity,
title = {Carrier escalation evidence packages: source note carrier-escalation-evidence-503-ambiguity},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/carrier-escalation-evidence-503-ambiguity},
note = {Source note carrier-escalation-evidence-503-ambiguity, checked 2026-09-24}
}