Claim record · SIP response codes and failure interpretation
A 401 Unauthorized response means the request requires user authentication; it is issued by user agent servers and registrars, distinct from 407 which is used by proxy servers.
fact · verified 2026-09-04
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- sip
- Deployment
- not restricted
- Region
- not restricted
- Release range
- not restricted
- Status
- fact
- Confidence
- 0.95
- Verified
- 2026-09-04
Sources
- SIP: Session Initiation Protocol (RFC 3261) — IETF · tier 1 standards and regulators · section-21.4.2
Cite this claim
APA
WarmTransfer. (2026, September 4). SIP response codes and failure interpretation: claim sip-401-unauthorized. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-401-unauthorized
BibTeX
@misc{warmtransfer-claim-sip-401-unauthorized,
title = {SIP response codes and failure interpretation: claim sip-401-unauthorized},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-401-unauthorized},
note = {Claim sip-401-unauthorized, verified 2026-09-04}
}