Analog modem emulator?

Essentially the layout would be this. I have a computer with 4 internal modems in it. Has to be internal, I can't do this with external modems/serial ports. Somehow I get it configured so that I can telnet from the internet to this "emulator" and it directs my telnet session to one of the 4 free analog lines. Now, there's some solutions like lantronix UDS devices, where the device has an ethernet jack and a 25 pin serial port and it can be set to emulate an external modem, so folks can telnet to this device and it then tricks the computer into thinking a modem connection is made... ...but my scenario is different in that I want the connection going to the PC to still be analog lines. So, this device would have to have some sort of modem emulation of its own. It sounds sort of off-the-wall, but I wanted to run it by the group to see if it rang any bells. Maybe there's some situation where such a device would have been developed, but I'm not seeing the connection yet. Perhaps if you were putting a multiline BBS system (that didn't support external modems) on a local LAN? Maybe that's stretching the boundaries of sensible communications a bit :) Pete