AUTOMATIC NUMBER IDENTIFICATION HAVING FOUR-PARTY DETECTION

摘要

AUTOMATIC NUMBER IDENTIFICATION HAVING FOUR-PARTY DETECTION An automatic number identification system in a tributary office having simultaneous dual operation for high traffic capacity. An identifier unit applying identification signals via a sleeve lead associated with the line of a calling station to multiple inputs of a common directory number network. Each of the multiple inputs corresponds with the directory number of one of the stations of the calling line. Stations associated with the line are inexpensively and quickly modified to provide passive response to a party test initiated by the identifier unit. Positive and negative current detectors connected to the line determine which of the appropriately marked stations is establishing a call, and the corresponding number network input is established to receive the identification signals.