Source note · Call transfer semantics REFER and Replaces
A REFER transaction carries no subscription duration in either the request or the response; the lifetime of the subscribed state follows the progress of the referenced request, and the duration is chosen by the agent accepting the REFER and communicated in the initial NOTIFY's Subscription-State expires parameter, which an agent unwilling to hold state may use to terminate the subscription immediately.
Checked 2026-09-16
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- REFER
- Deployment
- not restricted
- Region
- not restricted
- Release range
- Standards Track
- Checked
- 2026-09-16
Sources
- RFC 3515 — The Session Initiation Protocol (SIP) Refer Method — IETF / RFC Editor · tier 1 standards and regulators · RFC 3515 section 2.4.4, final paragraph
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-refer-subscription-duration-is-the-notifiers. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-refer-subscription-duration-is-the-notifiers
BibTeX
@misc{warmtransfer-claim-xfersem-refer-subscription-duration-is-the-notifiers,
title = {Call transfer semantics REFER and Replaces: source note xfersem-refer-subscription-duration-is-the-notifiers},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-refer-subscription-duration-is-the-notifiers},
note = {Source note xfersem-refer-subscription-duration-is-the-notifiers, checked 2026-09-16}
}