SIP 488 Not Acceptable Here
KamailioRFC 3261 §21.4.26The destination accepted the request but cannot honour the SDP offer. The classic codec-mismatch error: the offered codecs don't intersect the callee's allow-list.
Common causes on Kamailio
- Codec mismatch (e.g. caller G.722 only, callee G.711 only)
- Transcoder offline or not configured
- SRTP required by one side but TLS/SIPS missing
- Wrong RTP IP/port from a NAT-broken UA
Kamailio-specific note
Kamailio doesn't transcode by default — it forwards SDP. A 488 here usually means the downstream UAS doesn't support the codecs you forwarded. Look at `sdp_get_line_startswith` or RTPProxy/RTPEngine codec masking modules.
Stop guessing — paste your trace
Drop your PCAP or sngrep log and SIP Flow will render the ladder, surface the failing transaction, and (optionally) ask Gemini to suggest the fix grounded in Kamailio docs.
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