Source note · SIP retransmission timers and transaction state
RFC 3261 names 8 lettered timers: A and E set a request retransmit interval starting at the round trip estimate B and F set a transaction timeout at 64 times it C sets a proxy timeout above 3 minutes G sets a response retransmit interval H sets the wait for an acknowledgement at 64 times the estimate and D I J and K set wait times for retransmissions to die out.
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-eight-lettered-timers. WarmTransfer. https://warmtransfer.net/knowledge/claims/siprt-eight-lettered-timers
BibTeX
@misc{warmtransfer-claim-siprt-eight-lettered-timers,
title = {SIP retransmission timers and transaction state: source note siprt-eight-lettered-timers},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/siprt-eight-lettered-timers},
note = {Source note siprt-eight-lettered-timers, checked 2026-09-15}
}