The present invention relates to an audio frequency signal identification apparatus for automatically identifying an audio frequency signal which appears on a telephone line in order to determine a service condition and the mode of the telephone line.
In an identification system of this type, types of signals are identified by analyzing a frequency spectrum and fluctuation over time of the frequency spectrum. This system is conventionally realized by an analog circuit as a line monitor arranged in a switching system.
For this reason, it is difficult to identify instantaneous voice data, identification precision is not so high, and a relatively long time is required for identification. Since the analog circuit is adopted, the hardware size is large even for several lines, and it is difficult to identify all the calls processed by the switching system at one time.
USPTO Backgrounds
USPTO Backgrounds