SIP 183 Session Progress vs 412 Conditional Request Failed
SIP 183 (Session Progress) is a 1xx Provisional response, while 412 (Conditional Request Failed) is a 4xx Client Failure response. 183 indicates that used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP. In contrast, 412 means that the precondition given in the request was not met. Used with SIP event state publication (RFC 3903).
Descrição
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Quando você o vê
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Como corrigir
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Descrição
The precondition given in the request was not met. Used with SIP event state publication (RFC 3903).
Quando você o vê
When a PUBLISH request includes an If-Match header with an entity tag that does not match the current state on the server.
Como corrigir
Refresh the entity tag by performing a new PUBLISH without If-Match, then use the returned SIP-ETag for subsequent updates.
Diferenças principais
183 is a 1xx Provisional response, while 412 is a 4xx Client Failure response.
SIP 183: Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
SIP 412: The precondition given in the request was not met. Used with SIP event state publication (RFC 3903).
You encounter 183 when during call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
You encounter 412 when when a PUBLISH request includes an If-Match header with an entity tag that does not match the current state on the server.
Quando usar qual
For 183 (Session Progress): No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA. For 412 (Conditional Request Failed): Refresh the entity tag by performing a new PUBLISH without If-Match, then use the returned SIP-ETag for subsequent updates.