RFC 3264 recommends that unless there is a specific reason the answerer lists formats in the same relative order as the offer, and gives the reason: it helps assure that the same codec is used in both directions.

Checked 2026-09-15

This helps assure that the same codec is used in both directions.
Vendor
IETF
Product
SIP
Subsystem
SDP offer/answer
Deployment
not restricted
Region
not restricted
Release range
RFC 3264
Checked
2026-09-15

Sources

Cite this note

APA

WarmTransfer. (2026, September 15). SDP offer answer and codec negotiation: source note sdp-oa-answerer-should-keep-the-offer-order. WarmTransfer. https://warmtransfer.net/knowledge/claims/sdp-oa-answerer-should-keep-the-offer-order

BibTeX

@misc{warmtransfer-claim-sdp-oa-answerer-should-keep-the-offer-order,
  title  = {SDP offer answer and codec negotiation: source note sdp-oa-answerer-should-keep-the-offer-order},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sdp-oa-answerer-should-keep-the-offer-order},
  note   = {Source note sdp-oa-answerer-should-keep-the-offer-order, checked 2026-09-15}
}

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