SIP 302 Moved Temporarily vs 491 Request Pending
SIP 302 (Moved Temporarily) is a 3xx Redirection response, while 491 (Request Pending) is a 4xx Client Failure response. 302 indicates that the callee has temporarily moved to a different address. The client should retry the request at the Contact address but continue using the original URI for future requests. In contrast, 491 means that the request was received by a UAS that had a pending request within the same dialog. The UAS cannot process both requests simultaneously.
説明
The callee has temporarily moved to a different address. The client should retry the request at the Contact address but continue using the original URI for future requests.
このコードが表示される場合
When a user is temporarily reachable at a different location, such as when traveling or using a different device.
解決方法
Redirect the current call to the Contact URI provided, but keep the original URI for future requests.
説明
The request was received by a UAS that had a pending request within the same dialog. The UAS cannot process both requests simultaneously.
このコードが表示される場合
When sending a re-INVITE while another re-INVITE is still being processed. Common during hold/unhold or codec change sequences.
解決方法
Wait for the pending transaction to complete before sending a new one. Implement proper glare handling (RFC 3261 Section 14.1).
主な違い
302 is a 3xx Redirection response, while 491 is a 4xx Client Failure response.
SIP 302: The callee has temporarily moved to a different address. The client should retry the request at the Contact address but continue using the original URI for future requests.
SIP 491: The request was received by a UAS that had a pending request within the same dialog. The UAS cannot process both requests simultaneously.
You encounter 302 when when a user is temporarily reachable at a different location, such as when traveling or using a different device.
You encounter 491 when when sending a re-INVITE while another re-INVITE is still being processed. Common during hold/unhold or codec change sequences.
どちらをいつ使うか
For 302 (Moved Temporarily): Redirect the current call to the Contact URI provided, but keep the original URI for future requests. For 491 (Request Pending): Wait for the pending transaction to complete before sending a new one. Implement proper glare handling (RFC 3261 Section 14.1).