RFC 3911 says a request carrying both Join and a header with contradictory semantics such as Replaces MUST be rejected with 400 Bad Request.

Checked 2026-09-24

Vendor
IETF
Product
SIP Join header
Subsystem
join
Deployment
any
Region
not restricted
Release range
RFC 3911 as published
Checked
2026-09-24

Sources

Cite this note

APA

WarmTransfer. (2026, September 24). Hold resume and conference signaling: source note hold-resume-conference-3911-join-with-replaces-400. WarmTransfer. https://warmtransfer.net/knowledge/claims/hold-resume-conference-3911-join-with-replaces-400

BibTeX

@misc{warmtransfer-claim-hold-resume-conference-3911-join-with-replaces-400,
  title  = {Hold resume and conference signaling: source note hold-resume-conference-3911-join-with-replaces-400},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/hold-resume-conference-3911-join-with-replaces-400},
  note   = {Source note hold-resume-conference-3911-join-with-replaces-400, checked 2026-09-24}
}

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