After a default installation, out of the box, you'll find that FreeSWITCH is already able to do an astonishing amount of things! We've put a lot of effort into writing the mother of all demos, and the configuration that gets installed by default is just that, a big FreeSWITCH demo. When we add a new feature to FreeSWITCH, when we write a new module, or when someone comes out with a novel, clever way to use FreeSWITCH, we add some lines to the example configuration. Please note, we'll repeat that again later, that the example demo configuration is not intended at all to be used in a production system. In it, you'll find a mine of snippets waiting for you to reuse, techniques to do things, and many different ways to organize information about users, gateways, applications, context, and scripts. It is an enormous repository of FreeSWITCH applied knowledge, and is working right at the end of installation. So, please use it until you feel acquainted with the basics of FreeSWITCH, and then come back to reading it when you're looking for a way to add a feature or execute a task.

In this chapter, we will cover the following topics:

• Important VoIP and FreeSWITCH concepts
• Using the FreeSWITCH command-line interface (fs_cli)
• Configuring a phone to work with FreeSWITCH
• Calling various extensions in the system