No, I haven't had either of mine plugged into a phone line for over 2 years now.
I have this same exact problem, exactly as you have described. I have 6.3, and now that there appears to be a fix for some of the problems I wonder how I am going to get it.When I ask it to call out to get the "call in numbers list" the modem performs as it should. When I request, or it decides to, make the daily call the connection fails stating the service did not answer. I call the number and there is service at the other end.