After a fresh install, out of the box, you'll find the "directory" main XML file located at /usr/local/freeswitch/conf/directory/default.xml . That main file will then include many other files, as we'll see.
Let's understand its most important lines.
First things first, we set the "domain" we're talking about. In SIP and in Verto, addresses are in the form "userid@domain", very much like in email (actually SIP borrowed this format from SMTP, the mail protocol, and Verto borrowed it from SIP). We can have multiple "domain" items, they would be added after the closing </domain> XML tag (not in the screenshot).
Then, a "params" XML container starts, surrounding the "param" items that belongs directly to the "domain" we're defining. Those "param" items will be linked to both the "users" that are contained into this domain, and the "group" items (then, the "user" items that belong to the "group" items) contained into the...