SIP 202 Accepted vs 437 Unsupported Certificate
SIP 202 (Accepted) is a 2xx Success response, while 437 (Unsupported Certificate) 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, 437 means that the server was unable to validate the certificate referenced by the Identity-Info header. The certificate may be self-signed or from an untrusted CA.
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 server was unable to validate the certificate referenced by the Identity-Info header. The certificate may be self-signed or from an untrusted CA.
When You See It
When the signing certificate for SIP Identity validation is not trusted by the verifying server.
How to Fix
Use a certificate from a trusted Certificate Authority. Ensure the certificate chain is complete and not expired.
Key Differences
202 is a 2xx Success response, while 437 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 437: The server was unable to validate the certificate referenced by the Identity-Info header. The certificate may be self-signed or from an untrusted CA.
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 437 when when the signing certificate for SIP Identity validation is not trusted by the verifying server.
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 437 (Unsupported Certificate): Use a certificate from a trusted Certificate Authority. Ensure the certificate chain is complete and not expired.