SIP 202 Accepted vs 423 Interval Too Brief
SIP 202 (Accepted) is a 2xx Success response, while 423 (Interval Too Brief) is a 4xx Client Failure response. 202 indicates that the request has been accepted for processing but the processing has not been completed. Used primarily for REFER requests. In contrast, 423 means that the expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
Description
The request has been accepted for processing but the processing has not been completed. Used primarily for REFER requests.
When You See It
After sending a REFER request for call transfer. The transfer target acknowledges receipt but hasn't completed the transfer yet.
How to Fix
Wait for a NOTIFY to learn the outcome of the referred action. If no NOTIFY arrives, check subscription state and network connectivity.
Description
The expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
When You See It
When a REGISTER or SUBSCRIBE request has an Expires value that is below the server's minimum. Common with aggressive keep-alive timers.
How to Fix
Increase the Expires header value to at least the Min-Expires value from the response.
Key Differences
202 is a 2xx Success response, while 423 is a 4xx Client Failure response.
SIP 202: The request has been accepted for processing but the processing has not been completed. Used primarily for REFER requests.
SIP 423: The expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
You encounter 202 when after sending a REFER request for call transfer. The transfer target acknowledges receipt but hasn't completed the transfer yet.
You encounter 423 when when a REGISTER or SUBSCRIBE request has an Expires value that is below the server's minimum. Common with aggressive keep-alive timers.
When to Use Which
For 202 (Accepted): Wait for a NOTIFY to learn the outcome of the referred action. If no NOTIFY arrives, check subscription state and network connectivity. For 423 (Interval Too Brief): Increase the Expires header value to at least the Min-Expires value from the response.