linux minicom

This is a utility which provide commandline interface to the serial port connected devices.
this is some what similar to the hyperterminal in windows
which also used for modem communications

configure minicom

minicom -s

set device(eg, ttyS0,) set baudrate say (9600 or parity hardware flow control etc).and etc...
save the configuration file

and in the root prompt

enter command

minicom

will connect device which you configured in the minicom.

(router interface with linux mechine is also done using minicom)