Use this procedure to set up hairpinning on a gateway. Hairpinning is sending a call back to the PSTN portion of the network if the call cannot be serviced by the Voice-over-IP (VoIP) portion of the network.
Prerequisite: The baseline dial plan has been defined and you are in the Design View.
1. Create a route scope for the hairpin route.
2. Set up an ingress route.
Set the dial peer type to both.
Enter a destination pattern (a dial string containing up to 32 digits and ending with the letter T.)
Set the priority to 1.
Set the address resolution authority (ARA) type to gatekeeper group (GKGrp), OSP server, or ipv4.
Assign the route scope that was created in Step 1.
3. Set up an egress route.
Use the same destination pattern as the ingress route created in Step 2.
Set the dial peer type to POTS.
Set the priority to a low level, such as 10.
Assign the route scope that was created in Step 1.