Check out this website: http://www.linmodems.org/
It has a wealth of information on modems, especially those found in laptops.
I am running linux in an IBM T40. The modem was needed as I have a dial-up. A little bit of configuring was needed but it didn't take long.
The best thing is to identify the chipset of the modem and see where you need to go from there. All of this is covered at the website link above.