Laptops usually come with internal (on-board) modems. Unfortunately, this almost always means they are “winmodems” whose functionality is implemented in software, for which only Windows® drivers are normally available (though a few drivers are beginning to show up for other operating systems; for example, if your modem has a Lucent LT chipset it might be supported by the comms/ltmdm port). If that is the case, you need to buy an external modem: the most compact option is probably a PC Card (PCMCIA) modem, discussed below, but serial or USB modems may be cheaper. Generally, regular modems (non-winmodems) should work fine.