USR Moden & Windows 2000

I am trying to install a USR 56k ext faxmodem on a PIII system w/ W2K. I cannot get the modem to communicate, dial etc. I have installed the proper driver and I seem to recall that there might have to be registry changes in order to get this thing to work,, but I can’t locate any doc. for that. HAs any pone else run into this? Please let me know. Thanks