If outgoing calls do not always or never work, then first perform the following checks:
I cannot select my TAPI driver in the configuration wizard
If the problem cannot be located, CTI Data Connector Enterprise Edition can log all events coming from the TAPI driver. Often wrong implementations of the TAPI driver or functions not implemented like call transferring are causing problems. Our support team can analyze the log file.
To send us a log file - see How do I send a log file?