In SIP an initial INVITE may carry an SDP offer in its body but is not required to; an INVITE without an offer is permitted by RFC 3261.

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

Cite this note

APA

WarmTransfer. (2026, September 25). SIP early offer and delayed offer: source note sip-early-delayed-offer-rfc3261-invite-offer-optional. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-early-delayed-offer-rfc3261-invite-offer-optional

BibTeX

@misc{warmtransfer-claim-sip-early-delayed-offer-rfc3261-invite-offer-optional,
  title  = {SIP early offer and delayed offer: source note sip-early-delayed-offer-rfc3261-invite-offer-optional},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-early-delayed-offer-rfc3261-invite-offer-optional},
  note   = {Source note sip-early-delayed-offer-rfc3261-invite-offer-optional, checked 2026-09-25}
}

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