Modem driver for Linux

Hi, my question is which modems are most commonly supported by Linux 7.1? I have 2 modems; a GVC F-1156iv/R9 and an Aopen fm56-pm but Linux does not have driver for them does it?
if it does how do I find it on GUI interface?
I tryed GVC and Aopen but they don’t have Linux driver for them, what would be the next thing to do?
do I need to buy a modem? if so what kind does Linux suppports?
Thanks!