Modem Auto Answer when shouldn't

I am using ras on my w2k3 enterprise box. I have it setup as a nat and only a
nat router, which works correctly. However, my modem now auto answers some of
my phone calls even though it is not set to. I have changed the numberofrings
key in the registy and that did not work. When i stop the service, my modem
does not answer. I even wiped the whole ras config and recreated all the
connections. I have no fax software installed on this box. It just started
doing this a month or two ago. I don't remember exactly when this started,
but there have been no significant software or hardware changes besides a new
modem. It could have coincided with a new windows update, i don't know. One
thing that i noticed is that when ras is running, the USR control center
software cannot find my modem. As soon as i stop the service, my modem shows
up in this software. I even reset the modem so it doesn't answer. I am out of
ideas here. I need to run ras and have it not answer my phone calls.