FXO to FXo is possible if you have a PBX/ Key System at each end. The FXO port on the router will connet to a Loop Start trunk port on the PBX/Key System. In this case the the PBX provides call suppervision.If you don't have a PBX/Key System and are ...

This should work just fine. There are some conditions though. Make sure you have enough bandwidth between these sites to allow free movement of packets. Besides this note the following:First condition is the point to point latency between these sites...