SIP 183 Session Progress vs 199 Early Dialog Terminated
Both SIP 183 (Session Progress) and 199 (Early Dialog Terminated) belong to the 1xx Provisional category. 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. Meanwhile, 199 means that a UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
説明
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
このコードが表示される場合
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
解決方法
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
説明
A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
このコードが表示される場合
In forked call scenarios when one of the forked branches is cancelled because another branch was answered.
解決方法
No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully.
主な違い
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 199: A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
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 199 when in forked call scenarios when one of the forked branches is cancelled because another branch was answered.
どちらをいつ使うか
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 199 (Early Dialog Terminated): No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully.