Source note · SIP retransmission timers and transaction state
Three constants underlie every SIP transaction timer: a round trip estimate defaulting to 500 milliseconds a maximum retransmit interval of 4 seconds for non-INVITE requests and INVITE responses and a maximum network lifetime of 5 seconds for a message.
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 appendix A, the timer table
Cite this note
APA
WarmTransfer. (2026, September 15). SIP retransmission timers and transaction state: source note siprt-three-base-constants. WarmTransfer. https://warmtransfer.net/knowledge/claims/siprt-three-base-constants
BibTeX
@misc{warmtransfer-claim-siprt-three-base-constants,
title = {SIP retransmission timers and transaction state: source note siprt-three-base-constants},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/siprt-three-base-constants},
note = {Source note siprt-three-base-constants, checked 2026-09-15}
}