If you just connect the phone to the microphone inlet on your computer, and not the line you may make a recording in Audacity. Then it is possible to analyze the signal if you are dialing. I use to just record 0 and look at that.
Here is how I learned it:
http://www.classicrotaryphones.com/f...5673#msg175673
Another option is to have a serial port, an RS232 and some fre software and it is much more easy to test.
http://www.classicrotaryphones.com/f...?topic=21454.0
dsk