SIP 183 Session Progress vs 408 Request Timeout
SIP 183 (Session Progress) is a 1xx Provisional response, while 408 (Request Timeout) 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, 408 means that the server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
Description
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Quand vous le voyez
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Comment résoudre
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Description
The server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
Quand vous le voyez
When the callee does not respond within the configured timeout (e.g., phone rings but is never answered, or the endpoint is unreachable).
Comment résoudre
Check if the callee's device is powered on and registered. Verify network connectivity. Consider adjusting the server's transaction timeout value.
Différences clés
183 is a 1xx Provisional response, while 408 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 408: The server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
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 408 when when the callee does not respond within the configured timeout (e.g., phone rings but is never answered, or the endpoint is unreachable).
Quand utiliser lequel
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 408 (Request Timeout): Check if the callee's device is powered on and registered. Verify network connectivity. Consider adjusting the server's transaction timeout value.