Zetafax unable to respond to incoming calls

Symptom 

The Zetafax log shows error messages such as the following when a call is received, even though faxes can be sent and received successfully with the Diva Media Board:

1. 05-03-02 08:27:53 CAPI-1 - (-) - Error signalled in response to alert request (Alert already sent by another application) 05-03-02 09:55:08 CAPI-1 - (E) - Unable to pass message to CAPI (System Resource error - e.g. no memory) 05-03-02 09:55:08 CAPI-1 - (E) - Unable to send CAPI 'connection response' message 05-03-02 09:55:08 CAPI-1 - (E) - Unable to respond to incoming call indicated by CAPI sub-system

Explanation 

When Zetafax starts up, it registers each CAPI device separately, resulting in multiple CAPI registrations. When a call is received, the call is presented to all listening instances (or 'applications'). Every listening instance will then try to pick up the call, but only one can succeed. 
The error messages above are logged by every instance that failed to answer the call.

Solution 

To prevent these messages from being logged, enable the 'Group Optimization' feature in the Dialogic Diva Configuration Manager.

Group optimization makes the Diva Media Board create application groups depending on the LISTEN parameters that each application passes to the adapter. Every incoming call is then distributed on a per-group basis instead of a per-application basis. Thus, only one idle application in a group - not every idle application that matches the incoming call - receives an indication of the call.

To enable group optimization go to Start ->All  Programs -> Dialogic Diva  -> Configuration Manager. 

Click on the CAPI service and set Group Optimization to yes. 

Open

Activate the configuration and restart the machine for the changes to take effect.