In older version of freebpx if you write somethng manually in the configuration files it was flushed by amp, i.e. you can configure it through the interface only. Is this this thing still present in freepbx?
And what are the supported types of extenstions that can be added through this interface?
Just create your conf files and use the include file function to call those pages.
Like this #include extensions_custom.conf
the _custom.conf pages should be safe to add to
If you need to create a custom extension create it in a custom file then login as the custom ext and use the forward option to forward it to a ext. created by the gui
that way you can include it your dail plan easy