Converters basically provides a translation between your binding source and destination.

Generally we use single level converters like (Bool to Visibility Converter), (Color to Brush Converter), (Enum to Bool converter) and list is endless..

Now consider a scenario in which we require Multi-level conversion i.e from A => B => C.

Lets take an example, Suppose we have Bool to Visibility Converter and Color to Bool converter, and we want a translation like Color to Visibility Conversion.

So instead of making Color To Visibility converter we can make some generic converter that allows us to do multilevel Conversion.

Below is the Code of that Multi level Converter

public class ValueConverterGroup : IValueConverter
  {
    #region Data
    /// <summary>
    /// Stores the list of values, on which the converter has to be applied.
    /// </summary>
    private readonly ObservableCollection<IValueConverter> converters = new ObservableCollection<IValueConverter>();

    /// <summary>
    /// Stores the dictionary, mapping of value with its conversion attribute.
    /// </summary>
    private readonly Dictionary<IValueConverter, ValueConversionAttribute> cachedAttributes = new Dictionary<IValueConverter, ValueConversionAttribute>();

    #endregion

    #region Constructor
    /// <summary>
    /// 
    /// </summary>
    public ValueConverterGroup()
    {
      this.converters.CollectionChanged += this.OnConvertersCollectionChanged;
    }

    #endregion

    #region Converters

    /// <summary>
    /// Returns the list of IValueConverters contained in this converter.
    /// </summary>
    public ObservableCollection<IValueConverter> Converters
    {
      get { return this.converters; }
    }

    #endregion

    #region IValueConverter Members

    object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
      object output = value;

      for (int i = 0; i < this.Converters.Count; ++i)
      {
        IValueConverter converter = this.Converters[i];
        Type currentTargetType = this.GetTargetType(i, targetType, true);
        output = converter.Convert(output, currentTargetType, parameter, culture);

        // If the converter returns 'DoNothing' then the binding operation should terminate.
        if (output == Binding.DoNothing)
          break;
      }

      return output;
    }

    object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
      object output = value;

      for (int i = this.Converters.Count - 1; i > -1; --i)
      {
        IValueConverter converter = this.Converters[i];
        Type currentTargetType = this.GetTargetType(i, targetType, false);
        output = converter.ConvertBack(output, currentTargetType, parameter, culture);

        // When a converter returns 'DoNothing' the binding operation should terminate.
        if (output == Binding.DoNothing)
          break;
      }

      return output;
    }

    #endregion

    #region Private Helpers

    #region GetTargetType

    /// <summary>
    /// Returns the target type for a conversion operation.
    /// </summary>
    protected virtual Type GetTargetType(int converterIndex, Type finalTargetType, bool convert)
    {
      // If the current converter is not the last/first in the list, 
      // get a reference to the next/previous converter.
      IValueConverter nextConverter = null;
      if (convert)
      {
        if (converterIndex < this.Converters.Count - 1)
        {
          nextConverter = this.Converters[converterIndex + 1];
          if (nextConverter == null)
            throw new InvalidOperationException("The Converters collection of the ValueConverterGroup contains a null reference at index: " + (converterIndex + 1));
        }
      }
      else
      {
        if (converterIndex > 0)
        {
          nextConverter = this.Converters[converterIndex - 1];
          if (nextConverter == null)
            throw new InvalidOperationException("The Converters collection of the ValueConverterGroup contains a null reference at index: " + (converterIndex - 1));
        }
      }

      if (nextConverter != null)
      {
        ValueConversionAttribute conversionAttribute = cachedAttributes[nextConverter];

        // If the Convert method is going to be called, we need to use the SourceType of the next 
        // converter in the list.  If ConvertBack is called, use the TargetType.
        return convert ? conversionAttribute.SourceType : conversionAttribute.TargetType;
      }

      // If the current converter is the last one to be executed return the target type passed into the conversion method.
      return finalTargetType;
    }

    #endregion // GetTargetType

    #region OnConvertersCollectionChanged

    void OnConvertersCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
      // The 'Converters' collection has been modified, so validate that each value converter it now
      // contains is decorated with ValueConversionAttribute and then cache the attribute value.

      IList convertersToProcess = null;
      if (e.Action == NotifyCollectionChangedAction.Add ||
        e.Action == NotifyCollectionChangedAction.Replace)
      {
        convertersToProcess = e.NewItems;
      }
      else if (e.Action == NotifyCollectionChangedAction.Remove)
      {
        foreach (IValueConverter converter in e.OldItems)
          this.cachedAttributes.Remove(converter);
      }
      else if (e.Action == NotifyCollectionChangedAction.Reset)
      {
        this.cachedAttributes.Clear();
        convertersToProcess = this.converters;
      }

      if (convertersToProcess != null && convertersToProcess.Count > 0)
      {
        foreach (IValueConverter converter in convertersToProcess)
        {
          object[] attributes = converter.GetType().GetCustomAttributes(typeof(ValueConversionAttribute), false);

          if (attributes.Length != 1)
            throw new InvalidOperationException("All value converters added to a ValueConverterGroup must be decorated with the ValueConversionAttribute attribute exactly once.");

          this.cachedAttributes.Add(converter, attributes[0] as ValueConversionAttribute);
        }
      }
    }
    #endregion
    #endregion
  }

And in Xaml simply define your Converters in a required order, like

<convert:ValueConverterGroup x:Key="colorToVisibilityConverter">
        <convert:ColorToBooleanConverter />
        <convert:BooleanToVisibilityConverter />
      </convert:ValueConverterGroup>

 and thats all. You can have n levels of conversion A => B => C => D.....N levels

For Sending Mail From Asp Page to Any Mobile No :

Preparation :Make an Account On "www.way2sms.com" with valid mobile number.

Step 1: (.aspx page)

First of all setup an aspx page with two TextBoxes And a button

TextBox1=For Mobile No.

TextBox2=For Text .

Button = For Submission .

Step 2: (.aspx.cs page)

make a method like  below

public void send(string uid, string password, string message, string no)

                {

                    HttpWebRequest myReq =

                    (HttpWebRequest)WebRequest.Create(“http://ubaid.tk/sms/sms.aspx?uid=” + uid + “&pwd=” + password +

                    “&msg=” + message + “&phone=” + no + “&provider=way2sms”);

                    HttpWebResponse myResp = (HttpWebResponse)myReq.GetResponse();

                    System.IO.StreamReader respStreamReader = new System.IO.StreamReader(myResp.GetResponseStream());

                    string responseString = respStreamReader.ReadToEnd();

                    respStreamReader.Close();

                    myResp.Close();

                }

Step 3:(OnButtonClick)

Call the method on click of Submit Button -

protected void Button1_Click(object sender, EventArgs e)

            {

                   send(“YOURMOBILENO”,”YOURPASSWORD”, TextBox2.Text, TextBox1.Text);

             }

Step 4: 

        Replace YOURMOBILENO with your username on Way2sms And ”YOURPASSWORD” with your way2sms password.

Step 5:

       Test The Service By Enter Mobileno in TextBox1 And Message In TextBox2 and click on button .

Note:Unable to send Message On DoNotDisturb (DND) Service  Activated Cell Number.