What it means
The destination cannot accept the media you offered. This is the classic codec or media negotiation failure. The two sides could not agree on an audio format or a secure transport.
SIP/2.0 488 Not Acceptable Here
Common causes
- No codec in common between the two sides
- A secure versus non-secure media mismatch, such as RTP/AVP offered to an endpoint that wants RTP/SAVP
- SRTP or DTLS settings that do not line up
- An unsupported media type or an unusual ptime
- An IPv4 versus IPv6 mismatch in the SDP
How to fix it
- Make sure both sides share at least one codec such as PCMU or PCMA
- Match the transport, RTP/AVP with RTP/AVP or RTP/SAVP with RTP/SAVP
- Align SRTP and DTLS settings on both ends
- Inspect the SDP offer and the answer side by side to spot the field that does not match
- Use the SDP analyzer to read the offer and answer clearly
See it in your own trace
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