SIP 300 Multiple Choices vs 606 Not Acceptable
SIP 300 (Multiple Choices) is a 3xx Redirection response, while 606 (Not Acceptable) is a 6xx Global Failure response. 300 indicates that the address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint. In contrast, 606 means that the user's agent was contacted successfully but some aspects of the session description (SDP) are not acceptable. Unlike 488, this is a global failure — no other server can satisfy this request.
Description
The address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint.
When You See It
When a user has multiple registered devices or contact addresses and the server cannot determine which one to use.
How to Fix
Select one of the provided Contact addresses and resend the request to that specific URI.
Description
The user's agent was contacted successfully but some aspects of the session description (SDP) are not acceptable. Unlike 488, this is a global failure — no other server can satisfy this request.
When You See It
When the callee definitively cannot accept any of the offered media types or codecs. Different from 488 which is location-specific.
How to Fix
Check the Warning header or response body for which session parameters are unacceptable. Modify the SDP offer to use compatible codecs and media types.
Key Differences
300 is a 3xx Redirection response, while 606 is a 6xx Global Failure response.
SIP 300: The address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint.
SIP 606: The user's agent was contacted successfully but some aspects of the session description (SDP) are not acceptable. Unlike 488, this is a global failure — no other server can satisfy this request.
You encounter 300 when when a user has multiple registered devices or contact addresses and the server cannot determine which one to use.
You encounter 606 when when the callee definitively cannot accept any of the offered media types or codecs. Different from 488 which is location-specific.
When to Use Which
For 300 (Multiple Choices): Select one of the provided Contact addresses and resend the request to that specific URI. For 606 (Not Acceptable): Check the Warning header or response body for which session parameters are unacceptable. Modify the SDP offer to use compatible codecs and media types.