
modem-cmd is a very simple program designed to send arbitrary AT commands
to your modem over a serial line.  For example:

  $ modem-cmd /dev/ttyUSB0 ATZ
  OK
  $ modem-cmd /dev/ttyUSB0 ATDT123456
  BUSY

Useful for scripting.  E.g. setup monitor software like nagios/nut/etc to
dial your cell number if an emergency is detected.

You can read more about AT commands recognized by modems at:

  http://en.wikipedia.org/wiki/Command_and_Data_modes_(modem)
