Claim record · SIP transactions dialogs and call setup
For every 2xx response the UAC receives to an INVITE, the UAC core generates a separate ACK sent directly by the transport layer rather than the transaction layer, reusing the INVITE's CSeq number but with the method changed to ACK.
fact · verified 2026-09-04
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- sip
- Deployment
- not restricted
- Region
- not restricted
- Release range
- not restricted
- Status
- fact
- Confidence
- 0.95
- Verified
- 2026-09-04
Sources
- SIP: Session Initiation Protocol (RFC 3261) — IETF · tier 1 standards and regulators · section-13.2.2.4
Cite this claim
APA
WarmTransfer. (2026, September 4). SIP transactions dialogs and call setup: claim sip-invite-ack-2xx. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-invite-ack-2xx
BibTeX
@misc{warmtransfer-claim-sip-invite-ack-2xx,
title = {SIP transactions dialogs and call setup: claim sip-invite-ack-2xx},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-invite-ack-2xx},
note = {Claim sip-invite-ack-2xx, verified 2026-09-04}
}