I have an issue over on https://issues.freepbx.org that I’ve been instructed to make a pull request for. I’ve done this before for other projects on github, but I’m uncertain where to do it for this request. I’ve been going in circles and most of the docs/wikis are not current for development.
If it’s a specific module then that GitHub repo should be in there. If it’s the base system itself I’d guess that would be here --> https://github.com/FreePBX/core/pulls. Never done it myself, just an uneducated guess!
They are all modules. The base FreePBX system is the module called framework. The core module contains “core” functionality: extensions, trunks, outbound & inbound routes. Now you can make slightly more-educated guesses. (Or bug fixes!)