ISDN Modem

Okay, I have a Courier I-Modem (ISDN) that I have on my server. The driver for this doesn’t auto answer under RAS. Everytime I reboot my server, the driver is replaced with a PNP driver from the operating system. Therefore, my ISDN does not work. I have to re-load the driver every time????
Does anyone know of this problem or heard of a fix? Please advise!