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.
Mô tả
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Khi bạn thấy mã này
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Cách khắc phục
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Mô tả
The server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
Khi bạn thấy mã này
When the callee does not respond within the configured timeout (e.g., phone rings but is never answered, or the endpoint is unreachable).
Cách khắc phục
Check if the callee's device is powered on and registered. Verify network connectivity. Consider adjusting the server's transaction timeout value.
Sự khác biệt chính
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).
Khi nào dùng cái nào
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.