SIP 202 Accepted vs 439 First Hop Lacks Outbound Support
SIP 202 (Accepted) is a 2xx Success response, while 439 (First Hop Lacks Outbound Support) 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, 439 means that the first outbound proxy does not support the SIP outbound mechanism (RFC 5626) that the UA is trying to use.
Descripción
The request has been accepted for processing but the processing has not been completed. Used primarily for REFER requests.
Cuándo lo verás
After sending a REFER request for call transfer. The transfer target acknowledges receipt but hasn't completed the transfer yet.
Cómo solucionarlo
Wait for a NOTIFY to learn the outcome of the referred action. If no NOTIFY arrives, check subscription state and network connectivity.
Descripción
The first outbound proxy does not support the SIP outbound mechanism (RFC 5626) that the UA is trying to use.
Cuándo lo verás
When a UA configured for SIP outbound connects to a proxy that doesn't support the outbound option-tag.
Cómo solucionarlo
Upgrade the outbound proxy to support RFC 5626, or configure the UA to not require outbound support.
Diferencias clave
202 is a 2xx Success response, while 439 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 439: The first outbound proxy does not support the SIP outbound mechanism (RFC 5626) that the UA is trying to use.
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 439 when when a UA configured for SIP outbound connects to a proxy that doesn't support the outbound option-tag.
Cuándo usar cada uno
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 439 (First Hop Lacks Outbound Support): Upgrade the outbound proxy to support RFC 5626, or configure the UA to not require outbound support.