Call-by-Call Service Selection uses the same route patterns and route preferences as Automatic Alternate Routing (AAR), Automatic Route Selection (ARS), and Generalized Route Selection (GRS). The system uses information that is assigned in the AAR, ARS, GRS route patterns to determine what service or facility to use on an outgoing Call-by-Call Service Selection call.

You can administer a variety of services to use a single trunk group. The system distributes traffic over all available trunks for increased efficiency. Then you can assign services that are used on incoming and outgoing Call-by-Call Service Selection calls.

Using Country Protocol 1, you can integrate services such as MEGACOM, ACCUNET, and INWATS onto a single ISDN trunk group, with flexible assignment of trunks to each service. Calls such as an incoming 800 service call that requires through-switching as an outgoing WATS call can be routed over the same facility.