SIP 183 Session Progress vs 504 Server Time-out
SIP 183 (Session Progress) is a 1xx Provisional response, while 504 (Server Time-out) is a 5xx Server 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, 504 means that the server did not receive a timely response from an external server it accessed while attempting to process the request. Different from 408 (client timeout).
Beschreibung
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Wann Sie es sehen
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Wie man es behebt
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Beschreibung
The server did not receive a timely response from an external server it accessed while attempting to process the request. Different from 408 (client timeout).
Wann Sie es sehen
When a proxy's request to a downstream server times out. The proxy itself is working, but the next hop is unresponsive.
Wie man es behebt
Check the downstream server's availability. Verify DNS resolution for the next-hop domain. Consider adjusting transaction timeout values.
Wesentliche Unterschiede
183 is a 1xx Provisional response, while 504 is a 5xx Server 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 504: The server did not receive a timely response from an external server it accessed while attempting to process the request. Different from 408 (client timeout).
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 504 when when a proxy's request to a downstream server times out. The proxy itself is working, but the next hop is unresponsive.
Wann welchen verwenden
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 504 (Server Time-out): Check the downstream server's availability. Verify DNS resolution for the next-hop domain. Consider adjusting transaction timeout values.