Sending SMS through vb.net aaplication

Dim SMSEngine As New SMSCOMMS("COM1")
   Dim i As Integer

 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        SMSEngine.Open() 'open the port
        SMSEngine.SendSMS() 'send the SMS
    End Sub

Public Class SMSCOMMS
    Private WithEvents SMSPort As SerialPort
    Private SMSThread As Thread
    Private ReadThread As Thread
    Shared _Continue As Boolean = False
    Shared _ContSMS As Boolean = False
    Private _Wait As Boolean = False
    Shared _ReadPort As Boolean = False
    Public Event Sending(ByVal Done As Boolean)
    Public Event DataReceived(ByVal Message As String)
    

    Public Sub New(ByRef COMMPORT As String)
        'initialize all values
        SMSPort = New SerialPort
        With SMSPort
            .PortName = COMMPORT
            .BaudRate = 19200
            .Parity = Parity.None
            .DataBits = 8
            .StopBits = StopBits.One
            .Handshake = Handshake.RequestToSend
            .DtrEnable = True
            .RtsEnable = True
            .NewLine = vbCrLf
        End With
    End Sub

    Public Function SendSMS() As Boolean
        If SMSPort.IsOpen = True Then
            'sending AT commands
            SMSPort.WriteLine("AT")
            SMSPort.WriteLine("AT+CMGF=1" & vbCrLf) 'set command message format to text mode(1)
            SMSPort.WriteLine("AT+CSCA=""+919869099994""" & vbCrLf) 'set service center address (which varies for service providers (idea, airtel))
            SMSPort.WriteLine("AT+CMGS=  + TextBox1.text + " & vbCrLf) ' enter the mobile number whom you want to send the SMS
            _ContSMS = False
            SMSPort.WriteLine("+ TextBox1.text +" & vbCrLf & Chr(26)) 'SMS sending
            MessageBox.Show(":send")
            SMSPort.Close()
        End If
    End Function

    Public Sub Open()
        If Not (SMSPort.IsOpen = True) Then
            SMSPort.Open()
        End If
    End Sub

    Public Sub Close()
        If SMSPort.IsOpen = True Then
            SMSPort.Close()
        End If
    End Sub