🚀 go-pugleaf

I have had several occasions on which I have trouble connecting in fax mode
with some fax machines, when I can connect at the same time with others. 
In particular, it seems that although the modem (a USR Winmodem 28.8, in
the current case), dials properly, when the answering fax machine answers
the line, the modem just doesn't recognize the fax (or perhaps vice-versa) 


My most recent experience was with a rather old Panasonic fax machine.
However, there are not any error-correction settings, etc on that machine.
Can anyone suggest a good reference on troubleshooting faxmodem
connections?  I have looked extensively on USR's website, but none of the
documents have helped so far.

Any help would be appreciated.

Blair Hadfield