SIP 301 Moved Permanently vs 491 Request Pending
SIP 301 (Moved Permanently) is a 3xx Redirection response, while 491 (Request Pending) is a 4xx Client Failure response. 301 indicates that the user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header. 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.
描述
The user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header.
何时出现
When a user has permanently changed their SIP address. All future calls should be directed to the new URI.
如何修复
Update your address book or routing tables to use the new Contact URI provided in the response.
描述
The request was received by a UAS that had a pending request within the same dialog. The UAS cannot process both requests simultaneously.
何时出现
When sending a re-INVITE while another re-INVITE is still being processed. Common during hold/unhold or codec change sequences.
如何修复
Wait for the pending transaction to complete before sending a new one. Implement proper glare handling (RFC 3261 Section 14.1).
主要区别
301 is a 3xx Redirection response, while 491 is a 4xx Client Failure response.
SIP 301: The user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header.
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 301 when when a user has permanently changed their SIP address. All future calls should be directed to the new URI.
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.
何时使用哪个
For 301 (Moved Permanently): Update your address book or routing tables to use the new Contact URI provided in the response. 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).