Your modem will be a winmodm.I'm also using winmodem Intel 537 in knoppix.
I installedd knoppix into Hard and compiled and installed drivers from www.linmodems.org.
My modem is also in COM3 in windows .
Now it is linked in to /dev/ham <- /dev/ttyS3 ..etc

Try at www.linmodem.org.

Can you give me the opuput of scanmodem program ??