A dial plan for a gateway in a packet based voice system provides call re-direct functionality to the system. The dial plan allows a gateway to process all incoming and outgoing calls for an enterprise, thereby minimizing required interface with an existing PBX. The dial plan identifies a given call as an incoming call from a data network, an incoming call from the PSTN, or an outgoing call from the PBX at an enterprise. The dial plan further identifies a desired route for transmitting the call to a desired destination. If the desired route is over a data network, the dial plan tests the route to determine its availability, and if it is not available determines an alternate re-direct route over the PSTN.