7.4. Serial console is not /dev/modem

In many Linux distributions the file /dev/modem is a symbolic link to the serial port containing a modem which is available for use.

Although the serial console is a serial port with a modem, we certainly don't want it used to place an outgoing call.

Check that /dev/modem does not point to the serial port being used for the console, say /dev/ttyS0. If it does, then remove the symbolic link.

bash$ ls -l /dev/modem
lrwxrwxrwx 1 root root 10 Jan 01 00:00 /dev/modem -> /dev/ttyS0
bash# rm /dev/modem