Source note · SIP retransmission timers and transaction state
Timer H sets the wait for an acknowledgement at 64 times the round trip estimate and its expiry is what ends a server transaction that never received one.
Checked 2026-09-15
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- transaction timers
- Deployment
- not restricted
- Region
- not restricted
- Release range
- current as of 2026-09-15
- Checked
- 2026-09-15
Sources
- RFC 3261 — SIP: Session Initiation Protocol — IETF / RFC Editor · tier 1 standards and regulators · RFC 3261 sections 17.2.1 and appendix A
Cite this note
APA
WarmTransfer. (2026, September 15). SIP retransmission timers and transaction state: source note siprt-timer-h-is-the-ack-deadline. WarmTransfer. https://warmtransfer.net/knowledge/claims/siprt-timer-h-is-the-ack-deadline
BibTeX
@misc{warmtransfer-claim-siprt-timer-h-is-the-ack-deadline,
title = {SIP retransmission timers and transaction state: source note siprt-timer-h-is-the-ack-deadline},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/siprt-timer-h-is-the-ack-deadline},
note = {Source note siprt-timer-h-is-the-ack-deadline, checked 2026-09-15}
}