606 6xx Global failure RFC 3261
SIP 606 Not Acceptable
The user's agent was contacted but some aspect of the session (media type, codec, bandwidth) is not acceptable anywhere.
Typical Q.850 / ISDN cause: 58 (Bearer capability not presently available)
Advertisement
Common causes
- No acceptable codec or media for any of the callee's devices.
- Video call to an audio-only endpoint, with no fallback.
How to fix it
- Offer a widely supported codec such as G.711, and allow audio-only fallback.
Seeing 606 on calls through a router or firewall? Check that SIP ALG is disabled. It causes a surprising number of SIP errors. Read why.
About 6xx responses
The request cannot succeed anywhere. The caller should not retry it elsewhere.