Q:

How to bind to a collection within a collection in WPF

I'm still at the early stages of learning WPF and have decided to try and write a fairly simple Contact Browser app to get to grips with the fundamentals. To add to the complexity I am using Objects from another application. 
So far I have been able to successfully bind a ListBox control to a Collection and display the Contact Names. In the middle of the screen I have a StackPanel with a CustomControl that displays further details of the Contact. This all works surprisingly well except for that fact that the Object Model for the Contact hides the PhoneNUmber field within a Collection of fields.
How can I bind/call a specific item within a collection of a bound object collection?
Here is some of my XAML, firstly the main ContactWindow:
<DockPanel Width="auto" Height="auto" Margin="8 8 8 8">
    <Border Height="56" HorizontalAlignment="Stretch" VerticalAlignment="Top" BorderThickness="1" CornerRadius="8" DockPanel.Dock="Top" Background="Beige">
        <TextBox Height="32" Margin="23,5,135,5" Text="Search for contact here" FontStyle="Italic" Foreground="#FFAD9595" FontSize="14" BorderBrush="LightGray"/>
    </Border>
    <ListBox x:Name="contactList" DockPanel.Dock="Left" Width="192" Height="auto" Margin="5 4 0 8" ItemsSource="{Binding}" DisplayMemberPath="FullName" />
    <Grid DataContext="{Binding ElementName=contactList, Path=SelectedItem}">
        <Grid.RowDefinitions>
            <RowDefinition Height="1*" />
            <RowDefinition Height="0.125*" />
        </Grid.RowDefinitions>
        <local:BasicContactCard Margin="8 8 8 8" />
        <Button Grid.Row="1" x:Name="exit" Content="Exit" HorizontalAlignment="Right" Width="50" Height="25" Click="exit_Click" />
    </Grid>
</DockPanel>

And here is the XAML for the BasicContactCard:
<DockPanel Width="auto  " Height="auto" Margin="8,8,8,8" >
    <Grid Width="auto" Height="auto" DockPanel.Dock="Top">
        <Grid.RowDefinitions>
            <RowDefinition Height="1*" />
            <RowDefinition Height="1*" />
            <RowDefinition Height="1*" />
            <RowDefinition Height="1*" />
        </Grid.RowDefinitions>
        <TextBlock x:Name="companyField" Grid.Row="0" Width="auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="8,8,8,8" Text="{Binding Company}" FontWeight="Bold" FontSize="15" />
        <TextBlock x:Name="contactField" Grid.Row="1" Width="auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="8,8,8,8" Text="{Binding FullName}" FontWeight="Bold" />
        <TextBlock x:Name="phoneField" Grid.Row="2" Width="auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="8,8,8,8" Text="{Binding Phone}"/>
        <TextBlock x:Name="emailField" Grid.Row="3" Width="auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="8,8,8,8" Text="{Binding ValidEmailAddress}"/>
    </Grid>
</DockPanel>

All the elements within the BasicContactCard except for the Phone are exposed as get-able properties from the Contact collection object that the Listbox is bound to except for the Phone which resides within a collection of Field objects that can be called in C# as 
Contact c = contacList[i];
string val = c.ContactFields.Item("Phone",FieldNameType.Alias);

I hope all that makes sense! Any help or pointers to resources would be really appreciated!
Viv

A:

Use a value converter to get the phone number.
XAML:
<UserControl.Resources>    
    <TestApp:PhoneNumberConverter x:Key="PhoneNumberConverter" />
</UserControl.Resources>

<TextBlock Text="{Binding ., Converter=StaticResource PhoneNumberConverter}}"/>

Code behind:
public class PhoneNumberConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Contact c = value as Contact;
        string phoneNr = c.ContactFields.Item("Phone", FieldNameType.Alias); 
        return phoneNr;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

