Abstract

A method is disclosed for processing call data among telephone switching offices and a remotely situated data base system for deriving call service information needed to complete special service calls, such as INward WATS (Wide Area Telephone Service) calls to a destination specified by the derived information. A network of local and toll offices compiles a special service call message including a caller dialed 800 number and an originating area code for the INWATS service and then transmits that message to the data base system over CCIS (Common Channel Interoffice Signalling) facilities including signal transfer systems. At the data base, the message is translated into a directory-unlisted number identifying an INWATS customer station designated to serve the call. Before the call is switched through the toll switching network under control of the unlisted number, the open/closed and busy/idle conditions of the INWATS station are checked at the data base to determine the availability of the station to serve the call. Traffic data is accumulated at the data base by originating area code and by the unlisted INWATS number. When the number of calls to the unlisted number per unit time exceeds a threshold, the data base instructs the telephone system to inhibit such calls from being served for a prescribed period.