Source note · SS7 and carrier interworking concepts
The cause a PSTN caller receives for a SIP 503 depends on the gateway: RFC 3398 recommends cause 38 but the Cisco IOS 15M&T default is cause 63, so gateway configuration should be checked before interpreting a release cause.
inferred · Checked 2026-09-24
- Vendor
- multi-vendor
- Product
- SIP-ISUP gateways
- Subsystem
- cause code mapping
- Deployment
- carrier, on-premises
- Region
- not restricted
- Release range
- current as of 2026-09-24
- Status
- inferred
- Checked
- 2026-09-24
Sources
- SIP Configuration Guide, Cisco IOS Release 15M&T - Configuring SIP Message Timer and Response Features — Cisco · tier 2 current vendor documentation · Section SIP - Configurable PSTN Cause Code Mapping compared with RFC 3398 Section 8.2.6.1
Cite this note
APA
WarmTransfer. (2026, September 24). SS7 and carrier interworking concepts: source note ss7-carrier-interworking-503-mapping-divergence. WarmTransfer. https://warmtransfer.net/knowledge/claims/ss7-carrier-interworking-503-mapping-divergence
BibTeX
@misc{warmtransfer-claim-ss7-carrier-interworking-503-mapping-divergence,
title = {SS7 and carrier interworking concepts: source note ss7-carrier-interworking-503-mapping-divergence},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/ss7-carrier-interworking-503-mapping-divergence},
note = {Source note ss7-carrier-interworking-503-mapping-divergence, checked 2026-09-24}
}