isdncard?

Hello list, I am wondering: are there cards on the market, that will answer both isdn- and analogcalls on a given MSN? What I want to do, is build a server that will answer incoming connections, regardless of the fact that they are initiated on an analog line or on another isdn line. At this time I made it with an ISDN-card, connected to a line, which is also connected to an a/b switch, a moduvox. If the incoming call is analog, then the switch will lead the call to a modem, which is used for dialing in. I wonder if this could not be done with one device? TIA Leen