USB Modem issues

Ever since I upgraded to Mountain Lion, my USB USRobotics 5637 no longer detects a dial tone. I have been in touch w USRobotics who say it is an Apple thing. I have another USB modem by ZOOM. It works on about 50% of my outgoing faxes. The others do not connect. But at least I know the cable phone lines is OK

I am using Moutain Lion 10.8.2 and faxing via Preview for some items, other from MacPractice EMR program and others from a variety of locations. I have never had issues with Lion or before.

I am using a iMac 3.06 GHz Intel Core i3.

My settings in System Preferences are:

1. Network>Advanced...I have tried using all options on the pull down screen for detecting dial tone with change. I have the USRobotics selected

2. Printer I have search for the fax driver, found the appropriate one for both the Zoom and USRobotics and selected them.

Yet, I cannot get it to work.

Help please.