SIP 182 Queued vs 604 Does Not Exist Anywhere
SIP 182 (Queued) is a 1xx Provisional response, while 604 (Does Not Exist Anywhere) is a 6xx Global 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, 604 means that the server has authoritative information that the user indicated in the Request-URI does not exist anywhere. Unlike 404, this is a definitive, global statement.
Description
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.
When You See It
In call center or queuing scenarios where the callee is busy but the system holds the call in a queue.
How to Fix
Wait for the call to be dequeued. If queuing is not desired, configure the server to reject calls instead of queuing them.
Description
The server has authoritative information that the user indicated in the Request-URI does not exist anywhere. Unlike 404, this is a definitive, global statement.
When You See It
When the user definitively does not exist on any server in the network. The server has authoritative knowledge, not just local.
How to Fix
The user does not exist. Verify the SIP URI or phone number. Unlike 404, retrying on other servers will not help.
Key Differences
182 is a 1xx Provisional response, while 604 is a 6xx Global 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 604: The server has authoritative information that the user indicated in the Request-URI does not exist anywhere. Unlike 404, this is a definitive, global statement.
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 604 when when the user definitively does not exist on any server in the network. The server has authoritative knowledge, not just local.
When to Use Which
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 604 (Does Not Exist Anywhere): The user does not exist. Verify the SIP URI or phone number. Unlike 404, retrying on other servers will not help.