linux and modems

[TUCBBS]

Hi, I have several questions about Linux and Modems.
1) What I must look to identify a winmodem?
2) If a modem is external, It's always a complete modem (not a
winmodem)? There are external winmodems?
3) There is any way to work with linux and a winmodem? I know that It's
not a true modem and afects the performance of the processor, but I can
buy one at almost 1/4 of the price of a good modem.
Thanks, Luis.