Method and apparatus for determining digits dialed using a selected algorithm

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG.
1 shows a basic flow chart to be utilized in implementing the required steps of the present invention.
The arrangement of FIG.
2 can be utilized to implement the techniques of FIG.
1.
Each of operational blocks 101 through 109 is shown only in conceptual form, and may be implemented by any software programmer in the art with a minimum level of skill.
Indeed, many of the required algorithms, such as prompting a user to enter a particular digit, are already available "off the shelf.
" The program is entered at start 101, which is immediately prior to the first digit of a sequence of digits being received.
For example, the telephone may be answered by the voice processing system, and the voice processing system transmits a greeting message along with a request for the remote user to enter an account number.
Start block 101 is intended to show the flow of control immediately prior to entry by the user of the first digit of the account number.
The voice processing system receives the first digit at block 102, and records a digital signal representation of the DPD sequence generated by the first digit.
At block 103, the spaces between the pulses of the first digit's DPD sequence are measured and recorded in the system's working memory.
The system then determines the maximum variation between any two periods of the first digit's sequence at block 104.
Block 105 then checks to see if the variation exceeds a threshold.
If so, control is transferred to block 106 where the user is promoted for a training digit.
Consider the situation where the variation are small, below the predetermined threshold.
This means that the period of the incoming DPD signal is virtually constant, and the dialed digit can be measured by simply dividing the length of the incoming signal by its own period.
Such being the case, control passes to block 109.
It has been found that such a technique works provided that the period of DPD pulses does not vary by more than ten percent