Click Ecsow menu Tools > Options > Voice Activity Detection tab as below.

<img src="http://www.ecsow.com/faq/images/voice-activity-detection.png" alt="" width="580" height="558" />You can specify a message for Answering Machine lines.  Also can specify a message for human answered lines.

If you want to play a message immediately when the line pickup, you can enable the play message immediately option.