We will be using the default install of Debian and installing Asterisk from source and compiling. Freepbx will be downloaded from the website and installed. More here
Consider that if you use a setup like this in a business with 5 or more phones, you can save thousands of dollars a year in call costs, hardware and licensing. Think about donating a portion of that money to some of the companies in this document so they can keep developing great applications like these.