If you want to use a modem only for MS Windows/Dos, then you can just install almost any modem and it will work OK. With a Linux PC it's not always this easy unless you use an external modem. All external modems should work OK (even if they are labeled "Plug and Play") But most new internal modems are Plug-and-Play (PnP) and have PnP serial ports. In some cases (depending both on the modem and your version of Linux) The PnP configuring is built into the serial driver so you don't need to do anything. If it's an ISA modem you may need to use the Linux "isapnp" program to configure it (but this is planned to be built into future drivers ??). See the Plug-and-Play-HOWTO and the isapnp docs for more information.
Since each modem has an associated serial port and the port has both hardware and software, there are four parts to configuring a modem:
Communication programs include aminicom, seyon, or
wvdial (for PPP) and mgetty) for dial-in. Such
communication programs require that you configure them although the
default configuration they come with may only need a little tweaking.
Unfortunately the communication program doesn't do the low-level PnP configuring of the serial port: setting its IO address and IRQ in both the hardware and the driver. If you are lucky, this will happen automatically when you boot Linux. Setting these in the hardware was formerly done by jumpers but today it's done by "Plug-and-Play" software.
But there's a serious problem: Linux (as of early 2001) is not a true Plug-and-Play operating system but the latest serial drivers handle Plug-and-Play for some serial posts (built-into internal modems). In other case you may need to use Plug-and-Play tools to set up the configuration although they are not always very user friendly. This may create a difficult problem for you. The next section will go into this in much more detail.