LER CAPTCHA DO SITE NO VB. NET

  using System;
using System.Drawing;
using System.IO;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Text.RegularExpressions;

namespace captcha
{
    public partial class FrmCaptcha : Form
    {
        private readonly CookieContainer _cookies = new CookieContainer();

        public FrmCaptcha()
        {
            InitializeComponent();
            picCaptcha.Image = new Bitmap(RequestCaptcha());
        }

        private void BtnRequestCaptchaClick(object sender, EventArgs e)
        {
            picCaptcha.Image = new Bitmap(RequestCaptcha());
        }

          private Stream RequestCaptcha()
        {
            var request = (HttpWebRequest)WebRequest.Create([Ô]http://www.afreesms.com/image.php?[Ô]);
            request.CookieContainer = _cookies;

            WebResponse response = request.GetResponse();
            return (response.GetResponseStream());
        }
 

  Imports System.Drawing
Imports System.IO
Imports System.Text
Imports System.Windows.Forms
Imports System.Net
Imports System.Text.RegularExpressions

Namespace captcha
	Public Partial Class FrmCaptcha
		Inherits Form
		Private ReadOnly _cookies As New CookieContainer()

		Public Sub New()
			InitializeComponent()
			picCaptcha.Image = New Bitmap(RequestCaptcha())
		End Sub

		Private Sub BtnRequestCaptchaClick(sender As Object, e As EventArgs)
			picCaptcha.Image = New Bitmap(RequestCaptcha())
		End Sub

		Private Function RequestCaptcha() As Stream
			Dim request = DirectCast(WebRequest.Create([Ô]http://www.afreesms.com/image.php?[Ô]), HttpWebRequest)
			request.CookieContainer = _cookies

			Dim response As WebResponse = request.GetResponse()
			Return (response.GetResponseStream())
		End Function
	End Class
End Namespace 

Citação:

End While

  Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        wb.Navigate([Ô]http://www.afreesms.com/freesms/[Ô]) , False)
        While wb.ReadyState <> WebBrowserReadyState.Complete
            Application.DoEvents()

        End While

        Call grabthecaptcha()

    End Sub

    Private Sub grabthecaptcha()
        Dim doc As mshtml.IHTMLDocument2 = wb.Document.DomDocument
        Dim imgrange As mshtml.IHTMLControlRange = CType(doc.body, mshtml.HTMLBody).createControlRange
        For Each img As mshtml.IHTMLImgElement In doc.imagens
            If img.getattribute([Ô]src[Ô]).ToString.Contains([Ô]http://www.afreesms.com/image.php?[Ô]) Then
                imgrange.add(img)
                imgrange.execCommand([Ô]copy[Ô], False, Nothing)
                PictureBox1.Image = Clipboard.GetDataObject.GetData(DataFormats.Bitmap)
                Exit For
            End If
        Next
    End Sub


End Class 

Citação:

Ao invés de fazer esse loop sem sentido esperando a página carregar, use o evento DocumentCompleted do WebBrowser....

  Private Sub btuCarregarDados_Click(sender As Object, e As EventArgs) Handles btuCarregarDados.Click
        With WebBrowser1.Document
            .GetElementById([Ô]smsto[Ô]).SetAttribute([Ô]value[Ô], txtNumber.Text)
            .GetElementById([Ô]6dd71d06e7e2339396fa7a46fe58029532b0[Ô]).SetAttribute([Ô]value[Ô], txtMessage.Text)
            .GetElementById([Ô]imgcode[Ô]).SetAttribute([Ô]value[Ô], txtCaptcha.Text)
            System.Threading.Thread.Sleep(3000)
            .GetElementById([Ô]submit[Ô]).InvokeMember([Ô]click[Ô])

        End With
    End Sub 

  <td valign=[Ô]top[Ô] style=[Ô]text-align:right[Ô]><strong>Message:  </strong></td>
        <td valign=[Ô]top[Ô]><textarea id=6dd71d06e7e2339396fa7a46fe58029532b0 onfocus=[Ô]setbg([ô]#d9ffd9[ô],this.id);[Ô] name=3d855b5bbaa26dd391f7741fa01954c377e40f onblur=[Ô]setbg([ô]#f0f5e6[ô],this.id)[Ô]></textarea>
<script type=[Ô]text/javascript[Ô]>$([ô]#6dd71d06e7e2339396fa7a46fe58029532b0[ô]).focus();</script><br /><input type=[Ô]text[Ô] id=[Ô]msgLen[Ô] name=[Ô]msgLen[Ô] style=[Ô]width:26px;[Ô] size=[Ô]1[Ô] maxlength=[Ô]3[Ô] value=[Ô]160[Ô] readonly /><span class=[Ô]sm[Ô]>  

Citação:

Cara,
Eu modifiquei seu exemplo um pouco mas eu acho que é o que você precisa.

Só tem um problema: mesmo colocando os dados como o site pede, sempre dá erro no celular do destinatário. Mesmo colocando +55219xxxxxxxx ou 219xxxxxxxx, ou +559xxxxxxxx sempre o site avisa que o [Ô]country[Ô] do destinatário está faltando.

O programa já está colocando os dados no site. Resta, agora, tentar descobrir qual é o formato do celular de destino que o site quer.
OBS: alterei a versão 2015.