SIP 100 Trying vs 182 Queued
Both SIP 100 (Trying) and 182 (Queued) belong to the 1xx Provisional category. 100 indicates that the request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses. Meanwhile, 182 means 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.
Description
The request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses.
When You See It
Immediately after sending an INVITE. The proxy has received the call and is searching for the callee. This is the SIP equivalent of a dial tone.
How to Fix
No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration.
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.
Key Differences
SIP 100: The request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses.
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.
You encounter 100 when immediately after sending an INVITE. The proxy has received the call and is searching for the callee. This is the SIP equivalent of a dial tone.
You encounter 182 when in call center or queuing scenarios where the callee is busy but the system holds the call in a queue.
When to Use Which
For 100 (Trying): No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration. 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.