SIP 204 No Notification vs 606 Not Acceptable
SIP 204 (No Notification) is a 2xx Success response, while 606 (Not Acceptable) is a 6xx Global Failure response. 204 indicates that the request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request. 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 request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
Quand vous le voyez
When subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
Comment résoudre
No fix needed. The subscription was accepted but there is no state change to notify about yet.
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.
Quand vous le voyez
When the callee definitively cannot accept any of the offered media types or codecs. Different from 488 which is location-specific.
Comment résoudre
Check the Warning header or response body for which session parameters are unacceptable. Modify the SDP offer to use compatible codecs and media types.
Différences clés
204 is a 2xx Success response, while 606 is a 6xx Global Failure response.
SIP 204: The request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
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 204 when when subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
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.
Quand utiliser lequel
For 204 (No Notification): No fix needed. The subscription was accepted but there is no state change to notify about yet. 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.