V92 MOH no working

I have a Gateway V92 Voice Modem with MOH software which had worked fine up until about a month or two ago. It just stopped working & I made sure I still had call waiting (which I did), but I couldn't figure out what had happened. Someone told me to enter an intialization string in the modem device manager under the advanced tab (which I did), and it solved my problem!! I was so excited. Now, this week, it has stopped working again, and I have checked to be sure the initialization string is still there (which it is). I don't know what has happened--I uninstalled & reinstalled my software & driver, but it still won't work. Any ideas?