Private Sub sendATCommand(ByVal m_ModemPort As Integer)
        Try
 
            ' Attempt to open the port.
            m_CommPort.Open(m_ModemPort, 115200, 8, _
              Rs232.DataParity.Parity_None, Rs232.DataStopBit.StopBit_1, 4096)
 
            ' Write an AT Command to the Port.
            m_CommPort.Write(Encoding.ASCII.GetBytes("AT" & Chr(13)))
            System.Threading.Thread.Sleep(200)
 
            Application.DoEvents()
            m_CommPort.Close()
 
        Catch ex As Exception
            ' Warn the user.
            MessageBox.Show("Unable to communicate with Modem")
        End Try
 
    End Sub