Source note · SIP registration failures
When a trace shows a second 401 or 407 in reply to a REGISTER that already carries Authorization or Proxy-Authorization, the likeliest reading is that the credentials (username, password or realm) were rejected, not that the first challenge went unanswered.
inferred · Checked 2026-09-25
- Vendor
- not restricted
- Product
- SIP
- Subsystem
- authentication
- Deployment
- any
- Region
- not restricted
- Release range
- current as of 2026-09-25
- Status
- inferred
- Checked
- 2026-09-25
Sources
- RFC 3665: Session Initiation Protocol (SIP) Basic Call Flow Examples — RFC Editor / IETF · tier 1 standards and regulators · Section 2.5 compared with Section 2.1
Cite this note
APA
WarmTransfer. (2026, September 25). SIP registration failures: source note sip-registration-failures-repeat-401-means-bad-creds. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-registration-failures-repeat-401-means-bad-creds
BibTeX
@misc{warmtransfer-claim-sip-registration-failures-repeat-401-means-bad-creds,
title = {SIP registration failures: source note sip-registration-failures-repeat-401-means-bad-creds},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-registration-failures-repeat-401-means-bad-creds},
note = {Source note sip-registration-failures-repeat-401-means-bad-creds, checked 2026-09-25}
}