Abstract

The specification discloses a system for automatically controlling the connection of telephone calls between a plurality of input telephone trunk lines at a user's dedicated telephone switching facility and a preset number of output telephone trunk lines. Circuitry is provided to receive user authorization code numbers from the user's facility and for comparing the user authorization code numbers with stored code numbers or with a specified algorithymic equation. A dial tone allowing further operation of the system is provided only if the user authorization code numbers match ones of the stored code numbers or is determined valid by the equation. The system receives dialing signals from an input telephone trunk line and in response thereto selects an available one of the output telephone trunk lines according to predetermined efficiency criteria. For example, calls are completed on all flat rate trunk lines (WATS, FX, tie lines and the like) prior to completing calls on variable rate lines (DDD or the like). The system then establishes audio connections between the calling input telephone trunk line and the selected available output telephone trunk line to complete the inter-city call. If all flat rate output telephone trunk lines are busy, an audio message is presented to the caller to indicate that the system will attempt to complete the call in a predetermined time period and to request that the caller hold. If a flat rate output telephone trunk line becomes available during the predetermined time period, the call is automatically completed. If the predetermined time period runs out without the call being completed, the system determines the priority of the caller. If the caller has a low priority, an error tone is generated and the caller is disconnected. If the caller has a high priority, the call is automatically completed on a variable rate direct dial line. If the caller has a special priority authorization code number, the predetermined time period is not initiated and the call is immediately connected through a variable rate direct dial line. Prior to the system connecting the caller to a variable rate direct dial line, a warning tone is generated. The caller may then either hang up if he does not wish to use the variable rate line or stay on the line to complete his call.