Answer tone received at answering-side gateway and first classification signal is transmitted to a calling-side gateway that generates an answer tone in response to the signal. A second forecasting model is built based on a second data collection having intervals aggregated from intervals of the first data collection, wherein the second forecasting model is at a different aggregation level than the first forecasting model. The tapered portion is located between the large-diameter portion and the tubular portion, and is formed in such a manner that the diameter thereof increases in a flaring manner from the one end of the tubular portion to the large-diameter portion. The lifting component is connected to the first clipping component and configured to drive the first clipping component to move back and forth. A warning generating unit generates an alarm that a replacement time of a timing belt has arrived in response to the control signal from the controller, such that when a timing belt is worn to a degree of breakage, a warning signal is given by a detection thereof so that a healthy timing belt should not be changed periodically.