SIP 199 Early Dialog Terminated vs 420 Bad Extension
SIP 199 (Early Dialog Terminated) is a 1xx Provisional response, while 420 (Bad Extension) 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, 420 means that the server did not understand the protocol extension specified in a Require or Proxy-Require header. The Unsupported header lists the unknown extensions.
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 server did not understand the protocol extension specified in a Require or Proxy-Require header. The Unsupported header lists the unknown extensions.
このコードが表示される場合
When the request includes a Require header with SIP extensions that the server does not support.
解決方法
Check the Unsupported header in the response. Remove the unsupported extension from the Require header or make it optional via Supported.
主な違い
199 is a 1xx Provisional response, while 420 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 420: The server did not understand the protocol extension specified in a Require or Proxy-Require header. The Unsupported header lists the unknown extensions.
You encounter 199 when in forked call scenarios when one of the forked branches is cancelled because another branch was answered.
You encounter 420 when when the request includes a Require header with SIP extensions that the server does not support.
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 420 (Bad Extension): Check the Unsupported header in the response. Remove the unsupported extension from the Require header or make it optional via Supported.