Source note · SIP early offer and delayed offer
If the initial INVITE contains no offer, the offer is carried in the first reliable non-failure response from the UAS (the 2xx in base RFC 3261) and the answer must then be carried in the ACK.
Checked 2026-09-25
- Vendor
- IETF
- Product
- SIP
- Subsystem
- offer-answer
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3261
- Checked
- 2026-09-25
Sources
- RFC 3261 — SIP: Session Initiation Protocol — IETF / RFC Editor · tier 1 standards and regulators · Section 13.2.1 Creating the Initial INVITE
Cite this note
APA
WarmTransfer. (2026, September 25). SIP early offer and delayed offer: source note sip-early-delayed-offer-rfc3261-offer-in-2xx-answer-ack. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-early-delayed-offer-rfc3261-offer-in-2xx-answer-ack
BibTeX
@misc{warmtransfer-claim-sip-early-delayed-offer-rfc3261-offer-in-2xx-answer-ack,
title = {SIP early offer and delayed offer: source note sip-early-delayed-offer-rfc3261-offer-in-2xx-answer-ack},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-early-delayed-offer-rfc3261-offer-in-2xx-answer-ack},
note = {Source note sip-early-delayed-offer-rfc3261-offer-in-2xx-answer-ack, checked 2026-09-25}
}