VS 2005 Caller ID code (sample included) ....but I need help!

'Code from reference sources used:
'http://www.vbforums.com/showthread.php?660753-Listening-to-the-Serial-Port-Need-help&highlight=Modem+As+New+IO.Ports.SerialPort
'http://www.vbforums.com/showthread.php?647989-Get-caller-ID-from-serialport!&highlight=Modem.Write%28AT%2BVCID%3D1+%26amp%3B+vbCrLf%29
'http://code.msdn.microsoft.com/windowsdesktop/SerialPort-Sample-in-VBNET-fb040fb2
 
Public Class Form1
 
    Private WithEvents SerialPort As New System.IO.Ports.SerialPort
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
        Me.CheckForIllegalCrossThreadCalls = False ' <--This will be underlined as error but seems to work OK
 
        With SerialPort
 
            .PortName = "Com3"   'for example
            .BaudRate = 9600
            .RtsEnable = True
 
            'If SerialPort.IsOpen = False Then SerialPort.Open()
            'SerialPort.Write("AT+VCID=1" & vbCrLf)
 
            Try
                .Open()
                SerialPort.Write("AT+VCID=1" & vbCrLf)
 
            Catch ex As Exception
 
            End Try
 
 
        End With
 
    End Sub
 
 
    Private Sub SerialPort_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort.DataReceived
 
        Dim DataFromPort As String = SerialPort.ReadExisting
 
        RichTextBox1.AppendText(DataFromPort) ' displays formatted caller ID info
 
        ' if NAME = UNAVAILABLE    then hang up the call
 
        If DataFromPort.Contains("UNAVAILABLE") Then
 
            'disconect the call
            'SerialPort.Write("AT+??" & vbCrLf) ' <-- not sure what to do here to hang up? 
 
        End If
 
    End Sub
 
End Class