Source note · Hold resume and conference signaling
RFC 4579 says a conference focus MUST include the isfocus feature parameter in its Contact header unless it wishes to hide that it is a focus.
Checked 2026-09-24
A focus MUST include the 'isfocus' feature parameter in the Contact header field unless the focus wishes to hide the fact that it is a focus.
- Vendor
- IETF
- Product
- SIP conferencing
- Subsystem
- conference focus
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 4579 (BCP 119)
- Checked
- 2026-09-24
Sources
- Session Initiation Protocol (SIP) Call Control - Conferencing for User Agents — IETF / RFC Editor · tier 1 standards and regulators · Section 4.2 Session Establishment
Cite this note
APA
WarmTransfer. (2026, September 24). Hold resume and conference signaling: source note hold-resume-conference-4579-isfocus. WarmTransfer. https://warmtransfer.net/knowledge/claims/hold-resume-conference-4579-isfocus
BibTeX
@misc{warmtransfer-claim-hold-resume-conference-4579-isfocus,
title = {Hold resume and conference signaling: source note hold-resume-conference-4579-isfocus},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/hold-resume-conference-4579-isfocus},
note = {Source note hold-resume-conference-4579-isfocus, checked 2026-09-24}
}