Your modem is a peripheral device to Linux, like a CD-ROM drive, hard drive, or a mouse. Your modem will be connected to a serial port, which means that one of the serial devices in the /dev directory actually points to your modem. You may notice that there's also a file, /dev/modem, which serves as a placeholder for your modem. Initially this file doesn't point to anything. To simplify your operations, so that applications like minicomand seyon need only refer to /dev/modem, you can create a symbolic link from the serial device connected to your modem to /dev/modem.
To do so, login as root and issue the command:
ln -sf /dev/ttyS X /dev/modem
where X is replaced by the number corresponding to the serial device that points to your modem. Table 11.1 shows how the proper command corresponds to the device by which your modem is known user DOS and Linux.