It would be overkill for a small community network to overcomplicate things. Most long distance wifi AP's can establish the point to point connection and act as an AP simultaneously and most can provide basic firewalling as necessary.You don't need one, but access points at least. And the smart way is to have a router nating/firewalled at each house/building.
Like I said. It is for a rural farm setting. So a few houses that want communication between them using voice/messaging.This will all depend on the solution, the scope? A PBX system can be used to implement a traditional telephone-like system, but you can do standard VoIP with Mumble and Teamspeak on your own network and still implement a directory through privileges and rooms.
It depends on your needs and why you would want to stay in communication without the need to utilise internet or Telkom so to speak.