The database tables created by Kamailio, along with the description of their columns, are documented in the tutorial available at:

If you haven’t read it so far, take a bit of time to check the details for the tables of the modules you are using. It can help to understand better the purpose of each field that you have to provision for Kamailio.

The database structure is created using kamdbctl, if you start now with it, guidelines can be found in the install tutorial:

Contributions to add more documentation for┬ádatabase structure are very appreciated. You can update xml files from source tree in src/lib/srdb1/schema/ and then make a pull request via Kamailio’s project.

Thank you for flying Kamailio!