A configuration file is required for each Asterisk module you wish to use. These .conf files contain channel definitions, describe internal services, define the locations of other modules, or relate to the dialplan. You do not need to configure all of them to have a functioning system, only the ones required for your configuration. Although Asterisk ships with samples of all of the configuration files, it is possible to start Asterisk without any of them. This will not provide you with a working system, but it clearly demonstrates the modularity of the platform.
If no .conf files are found, Asterisk will make some decisions with respect to modules. For example, the following steps are always taken:
This appendix starts with an in-depth look at the modules.conf configuration file. We'll then briefly examine all the other files that you may need to configure for your Asterisk system.