SIP 199 Early Dialog Terminated vs 480 Temporarily Unavailable
SIP 199 (Early Dialog Terminated) is a 1xx Provisional response, while 480 (Temporarily Unavailable) is a 4xx Client Failure response. 199 indicates that a UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs. In contrast, 480 means that the callee's end system was contacted successfully but the callee is currently unavailable. The client may retry after some time.
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.
説明
The callee's end system was contacted successfully but the callee is currently unavailable. The client may retry after some time.
このコードが表示される場合
When the user exists but is not currently reachable — phone is off, DND mode enabled, or all lines are busy.
解決方法
Try calling again later. Check if the callee has DND enabled or if their device is powered off. Configure voicemail for unavailable scenarios.
主な違い
199 is a 1xx Provisional response, while 480 is a 4xx Client Failure response.
SIP 199: A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
SIP 480: The callee's end system was contacted successfully but the callee is currently unavailable. The client may retry after some time.
You encounter 199 when in forked call scenarios when one of the forked branches is cancelled because another branch was answered.
You encounter 480 when when the user exists but is not currently reachable — phone is off, DND mode enabled, or all lines are busy.
どちらをいつ使うか
For 199 (Early Dialog Terminated): No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully. For 480 (Temporarily Unavailable): Try calling again later. Check if the callee has DND enabled or if their device is powered off. Configure voicemail for unavailable scenarios.