Digit analysis system for private automatic branch exchange telephone system

Claim 1

In a common control type private automatic branch exchange telephone system having a memory containing a plurality of storage positions for storing the respective digits identifying a called number in response to dialed number information and a digit decoder for analyzing the contents of said memory and for supplying to the common control circuits of said system signals representative of further action which is necessary for processing the call, the improvement wherein said digit decoder comprises first means, responsive to the reception of a first complete digit in the called number, for storing a prescribed digital code, the value of which is not exclusively established to correspond to the value of said first complete digit, in a first selected one of said plurality of storage positions within said memory; second means, responsive to the reception of respective subsequent complete digits in the called number, for storing respective digital codes, corresponding to the values of said subsequent complete digits in respective selected ones of said plurality of storage positions within said memory; and third means, responsive to the reception of the last complete digit necessary for identifying the course of action to be taken by the system, for supplying a signal representative thereof to said common control circuits, and wherein the number of said plurality of storage positions within said memory corresponds to the number of digits identifying the line circuits within said system and wherein said decoder includes fourth means for storing each respective consecutively received digit in the same selected storage position as it is received for analysis by the decoder and for subsequently clearing said same selected storage position upon the completion of the processing of each received digit which is followed by a subsequent digit necessary for complete analysis of the called number.