I have downloaded the application, and upon starting it I was presented a menu with multiple choices. This indicates that the software can work in multiple ways. However, after you select an option, the wizard continues the configuration based on your settings. You need to obtain the configuration settings from the server admin if you use A PBX or not in order to configure the application.
Just select the option that suits you the best and then follow the wizard's instructions.
Download application: http://www.nch.com.au/ivm/
Tip: Use the links on the right to access the pages that provide information related to configuration/installation.