Because standards and gateway defaults collapse several distinct PSTN causes into 404, the SIP code alone cannot tell an unassigned number from a routing failure; the Q.850 cause in a Reason header, where present, is the better discriminator.
inferred · Checked 2026-10-02
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- Diagnosis
- Deployment
- any
- Region
- not restricted
- Release range
- current as of 2026-10-02
- Status
- inferred
- 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 table, read together with RFC 6432 section 3
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting SIP 404 Not Found and 484 Address Incomplete call failures: source note sip-404-484-troubleshooting-404-many-to-one. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-404-484-troubleshooting-404-many-to-one
BibTeX
@misc{warmtransfer-claim-sip-404-484-troubleshooting-404-many-to-one,
title = {Troubleshooting SIP 404 Not Found and 484 Address Incomplete call failures: source note sip-404-484-troubleshooting-404-many-to-one},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-404-484-troubleshooting-404-many-to-one},
note = {Source note sip-404-484-troubleshooting-404-many-to-one, checked 2026-10-02}
}