SIP 202 Accepted vs 481 Call/Transaction Does Not Exist
SIP 202 (Accepted) is a 2xx Success response, while 481 (Call/Transaction Does Not Exist) is a 4xx Client Failure response. 202 indicates that the request has been accepted for processing but the processing has not been completed. Used primarily for REFER requests. 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
The request has been accepted for processing but the processing has not been completed. Used primarily for REFER requests.
何时出现
After sending a REFER request for call transfer. The transfer target acknowledges receipt but hasn't completed the transfer yet.
如何修复
Wait for a NOTIFY to learn the outcome of the referred action. If no NOTIFY arrives, check subscription state and network connectivity.
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
202 is a 2xx Success response, while 481 is a 4xx Client Failure response.
SIP 202: The request has been accepted for processing but the processing has not been completed. Used primarily for REFER requests.
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 202 when after sending a REFER request for call transfer. The transfer target acknowledges receipt but hasn't completed the transfer yet.
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 202 (Accepted): Wait for a NOTIFY to learn the outcome of the referred action. If no NOTIFY arrives, check subscription state and network connectivity. 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.