Method for monitoring telephone call progress

摘要

A call progress monitor and algorithm for placing a telephone call over the telephone lines. The algorithm is hierarchically arranged having three major routines or portions: tone detection, signal recognition and situation recognition. The tone detection portion of the algorithm measures the power at each of a predetermined number of frequencies of interest. In accordance with one improvement, the data is sampled at a fraction of the rate at which it is supplied, for example, on a T1 channel. The signal recognition portion of the algorithm detects the presence of a particular signal and this stage of the algorithm has been modified to more precisely detect voice. Specifically, power within a voice filter band is compared with power at other predetermined frequencies and a decision is made based on this information. Furthermore, another improved aspect is that data for an entire Epoch is accumulated and stored in a buffer prior to processing as a group. The situation recognition portion of the algorithm determines that a certain sequence or pattern of signals has occurred with a particular timing or cadence.