Command:   modem - switch the modem and getty state
Syntax:    modem [-o] [-i num] ttyn
Flags:     -o  Turn getty off and set modem to dialout
           -i  Set line to dialin
Examples:  modem -o tty00           # Set tty00 to dialout
           modem -i2 tty00          # Set tty00 to dialin (2 rings)

     The getty program allows a terminal port to be used for both dialin
and  dialout.  This  little  program  switches the getty state, and also
sends some commands to the modem attached to the specified line.  If the
-o  flag  is presnt, modem will put the getty process (if any) connected
to the specified line into SUSPEND state, which means that it  will  not
pay  attention  to  that line until it is reset to RESTART state.  Also,
modem will send some (Hayes) commands to the attached modem  to  disable
the  auto-nanswer  mode.  The  -i flag specifies the number of times the
telephone has to ring before the modem may answer the call (to give  the
operator a chance).