Under RFC 8760 a UAS may send several WWW-Authenticate or Proxy-Authenticate headers in order of preference, and a UAC seeing several for the same realm should use the topmost one it supports.

Checked 2026-09-25

Vendor
not restricted
Product
SIP
Subsystem
authentication
Deployment
any
Region
not restricted
Release range
RFC 8760
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). SIP registration failures: source note sip-registration-failures-multi-challenge-order. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-registration-failures-multi-challenge-order

BibTeX

@misc{warmtransfer-claim-sip-registration-failures-multi-challenge-order,
  title  = {SIP registration failures: source note sip-registration-failures-multi-challenge-order},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-registration-failures-multi-challenge-order},
  note   = {Source note sip-registration-failures-multi-challenge-order, checked 2026-09-25}
}

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