If the ARS feature determines that a placed call is to be routed on-net, the call is handled over private network facilities. There are many private network configurations, ranging from support of a single station user working at home, to linking of dozens or hundreds of PBX systems and locations scattered across the globe. Private networking options can be classified according to the following criteria:

1. Number of PBX systems in the network design

2. Number of station users at each network location

3. Locations of station users relative to a local PBX system

4. Available transmission carrier facilities

5. Traffic capacity requirements between network locations

6. Feature transparency requirements across the network

7. Survivability requirements for each network location

8. Operations, management, maintenance, and service procedures