I've observed that the functionality of "sip-server secondary" appears to be triggered exclusively in the presence of a timeout or a 503 error. We encountered an issue where a carrier returned a "404 not found" error, yet the Adtran device did not successfully switch over to the secondary SIP server.
Is there a possibility that I'm overlooking something important in this context?
or adtran does not support failover for a 404 error ?