a minimalistic modem where much of the hardware has been replaced by specialised software
a modem stripped of much of its normal hardware, and which as a result depends on special emulation software in the Microsoft Windows operating system
a modem which uses the CPU for processing it's data
an internal chip kinda thing that functions as a modem and you probably won't have much luck getting it to work under Linux
a software modem designed to work with the Microsoft Windows operating system