Telephone answering device with improved end signal detection

摘要

A telephone answering device (TAD) detects termination signals (Calling Party Control or CPC signals) on a telephone line by determining which signal is most probably a CPC signal, then comparing suspect signals to the determined signal. A series of memory registers store the value of an initial series of suspected CPC signals when the TAD is initially powered up. The stored values are compared with each other to confirm and validate the CPC signal. Upon finding a sufficiently repeated value, that value is stored and from there on used as the value for the CPC signal. Future signals received that are the same as the determined CPC signal terminate TAD operation.