SIP 199 Early Dialog Terminated vs 481 Call/Transaction Does Not Exist
SIP 199 (Early Dialog Terminated) is a 1xx Provisional response, while 481 (Call/Transaction Does Not Exist) 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, 481 means that the UAS received a request that does not match any existing dialog or transaction. The call state may have been lost.
描述
A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
何时出现
In forked call scenarios when one of the forked branches is cancelled because another branch was answered.
如何修复
No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully.
描述
The UAS received a request that does not match any existing dialog or transaction. The call state may have been lost.
何时出现
When sending a BYE, re-INVITE, or UPDATE for a call that the server has no record of. Common after server restarts.
如何修复
The dialog has been lost. Terminate the local call state. For re-INVITE failures, re-establish the call from scratch.
主要区别
199 is a 1xx Provisional response, while 481 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 481: The UAS received a request that does not match any existing dialog or transaction. The call state may have been lost.
You encounter 199 when in forked call scenarios when one of the forked branches is cancelled because another branch was answered.
You encounter 481 when when sending a BYE, re-INVITE, or UPDATE for a call that the server has no record of. Common after server restarts.
何时使用哪个
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 481 (Call/Transaction Does Not Exist): The dialog has been lost. Terminate the local call state. For re-INVITE failures, re-establish the call from scratch.