SIP 182 Queued vs 491 Request Pending
SIP 182 (Queued) is a 1xx Provisional response, while 491 (Request Pending) is a 4xx Client Failure response. 182 indicates that the called party is temporarily unavailable but the server has decided to queue the call rather than reject it. The call will be attempted when the callee becomes available. 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.
الوصف
The called party is temporarily unavailable but the server has decided to queue the call rather than reject it. The call will be attempted when the callee becomes available.
متى تراه
In call center or queuing scenarios where the callee is busy but the system holds the call in a queue.
كيفية الإصلاح
Wait for the call to be dequeued. If queuing is not desired, configure the server to reject calls instead of queuing them.
الوصف
The request was received by a UAS that had a pending request within the same dialog. The UAS cannot process both requests simultaneously.
متى تراه
When sending a re-INVITE while another re-INVITE is still being processed. Common during hold/unhold or codec change sequences.
كيفية الإصلاح
Wait for the pending transaction to complete before sending a new one. Implement proper glare handling (RFC 3261 Section 14.1).
الفروق الرئيسية
182 is a 1xx Provisional response, while 491 is a 4xx Client Failure response.
SIP 182: The called party is temporarily unavailable but the server has decided to queue the call rather than reject it. The call will be attempted when the callee becomes available.
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 182 when in call center or queuing scenarios where the callee is busy but the system holds the call in a queue.
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.
متى تستخدم أيًا منهما
For 182 (Queued): Wait for the call to be dequeued. If queuing is not desired, configure the server to reject calls instead of queuing them. 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).