Source note · SIP registration failures
A registrar or UAS challenges with 401 Unauthorized and a WWW-Authenticate header, which the UA answers with Authorization; a proxy challenges with 407 Proxy Authentication Required and a Proxy-Authenticate header, which the UA answers with Proxy-Authorization.
Checked 2026-09-25
- Vendor
- not restricted
- Product
- SIP
- Subsystem
- authentication
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3261 as updated
- Checked
- 2026-09-25
Sources
- RFC 3261 — SIP: Session Initiation Protocol — IETF / RFC Editor · tier 1 standards and regulators · Sections 22.2 (User-to-User Authentication) and 22.3 (Proxy-to-User Authentication)
Cite this note
APA
WarmTransfer. (2026, September 25). SIP registration failures: source note sip-registration-failures-401-vs-407. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-registration-failures-401-vs-407
BibTeX
@misc{warmtransfer-claim-sip-registration-failures-401-vs-407,
title = {SIP registration failures: source note sip-registration-failures-401-vs-407},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-registration-failures-401-vs-407},
note = {Source note sip-registration-failures-401-vs-407, checked 2026-09-25}
}