Following the recent discussion on sr-users mailing list related to extensions available for various editors (e.g., vim, atom, vscode) that add syntax highlighting for kamailio.cfg, Juha Heinenen contributed the initial version of a such extension for Emacs editor.
It is now available in a github repository:
Besides syntax highlighting, it should also help to auto-indent the file, inherited from c-mode of emacs.
Should you want to contribute to this emacs extension, propose the changes via pull requests.
Of course, if you want to contribute kamailio.cfg syntax highlighting for other editors or file formatters, you are more that welcome to do it. Announce it on sr-users mailing list and from there we will find a proper place to host it or link to it from the website.
Thanks for flying Kamailio!