SDES a=crypto attributes are defined only for SRTP transports such as RTP/SAVP and RTP/SAVPF, not for plain RTP/AVP.

Checked 2026-09-25

SRTP security descriptions MUST only be used with the SRTP transport (e.g., "RTP/SAVP" or "RTP/SAVPF").
Vendor
IETF
Product
SDES
Subsystem
SRTP keying
Deployment
any
Region
not restricted
Release range
RFC 4568
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). SIP 488 and codec negotiation failures: source note sip-488-codec-failures-sdes-srtp-only. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-488-codec-failures-sdes-srtp-only

BibTeX

@misc{warmtransfer-claim-sip-488-codec-failures-sdes-srtp-only,
  title  = {SIP 488 and codec negotiation failures: source note sip-488-codec-failures-sdes-srtp-only},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-488-codec-failures-sdes-srtp-only},
  note   = {Source note sip-488-codec-failures-sdes-srtp-only, checked 2026-09-25}
}

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