SIP 200 OK vs 437 Unsupported Certificate
SIP 200 (OK) is a 2xx Success response, while 437 (Unsupported Certificate) is a 4xx Client Failure response. 200 indicates that the request has succeeded. For INVITE, the call has been answered. For other methods, the action has been completed successfully. 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 succeeded. For INVITE, the call has been answered. For other methods, the action has been completed successfully.
When You See It
When a call is answered (INVITE 200 OK), a registration succeeds (REGISTER 200 OK), or a subscription is accepted (SUBSCRIBE 200 OK).
How to Fix
No fix needed — this is a success response. The caller should send an ACK to complete the three-way handshake for INVITE transactions.
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
200 is a 2xx Success response, while 437 is a 4xx Client Failure response.
SIP 200: The request has succeeded. For INVITE, the call has been answered. For other methods, the action has been completed successfully.
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 200 when when a call is answered (INVITE 200 OK), a registration succeeds (REGISTER 200 OK), or a subscription is accepted (SUBSCRIBE 200 OK).
You encounter 437 when when the signing certificate for SIP Identity validation is not trusted by the verifying server.
When to Use Which
For 200 (OK): No fix needed — this is a success response. The caller should send an ACK to complete the three-way handshake for INVITE transactions. For 437 (Unsupported Certificate): Use a certificate from a trusted Certificate Authority. Ensure the certificate chain is complete and not expired.