Security dialing system for long distance telephone systems

Abstract

An automatic dialing system (ADS) for Touch Tone single or multiple trunk telephone systems that allows access to long distance dialing services including the access phone number of the service and the individual access code. The ADS used in a multiple trunk system with several key type telephones may be connected in parallel to any one existing telephone in the system and will serve all the telephones in the system. The system consists of a microprocessor that performs all the logic timing and control for the system, a phase lock loop that provides a near square wave output only when a selected single frequency is present, a solid state dialer that outputs to the telephone trunk the preprogrammed touch tone dial tones, a programmable non-volatile electrically alterable memory which provides easy programming of the service access telephone number and the individual access code and trunk isolation transformers. The phase lock loop and processor determines if the proper two buttons on the telephone keypad are pressed to initiate the sequence. The phase lock loop sequentially scans the trunk lines via a solid state switch for each trunk until the processor recognizes the access tone at which time the sequencer is stopped and the ADS captures the trunk and begins automatic dialing of the stored numbers.