So-called Winmodems, host-based, HCF-, HSP-, HSF-, controllerless, host-controlled, and soft modems require vendor- supplied software to do the work of proper hardware modems. The sale of these devices for x86-based PCs is becoming increasingly popular among retailers and OEMs because of their lower cost.
WinModems are not modems
http://www.idir.net/~gromitkc/winmodem.html
Linux Winmodem support: http://www.linmodems.org/
Related:
Modem