&D2      &D0 = means the modem should ignore the DTR Data
          Terminal Ready line from the computer.  When the
          computer asks the modem to hang up, by dropping DTR,
          the modem should thumb its nose at the computer and
          refuse.  NEVER USE &D0.
          &D1 = the modem refuses to hang up the phone, but at
          least it then sits panting like a dog, awaiting some
          command.  NEVER USE &D1.
          &D2 = means the modem should pay attention to DTR and
          hang up the phone when the computer drops DTR.  ALWAYS
          USE &D2.
          &D3 is like &D2 except the modem ALSO resets and
          forgets all its commands.  NEVER USE &D3.