Format TextBox for phone number in WPF

I have a DataGrid in a WPF window. How can I display a phone number string column in the DataGrid in a format of "(999)999-9999"?

The Phone number column in the DataGrid uses a TextBlock in the CellTemplate and a TextBox in the CellEditingTemplate. The phone number is stored as a string with no formatting such as "9995551234".

Is it possible to display the phone as: (999)555-1234 and edit it as (999)555-1234?

Try using Text="{Binding PhoneNumber, StringFormat={}{0:(###)###-####}}"

Edit

If your PhoneNumber property is of type string, then there's not really a lot you can do with StringFormat to format it.

In the past when I've wanted to do something like this, I expose a property called FormattedPhoneNumber which returns the formatted phone number for display purposes, and the edit box just binds to plain old unformatted PhoneNumber

public string FormattedPhoneNumber
{
    get
    {
        if (PhoneNumber == null)
            return string.Empty;

        switch (PhoneNumber.Length)
        { 
            case 7:
                return Regex.Replace(PhoneNumber, @"(\d{3})(\d{4})", "$1-$2");
            case 10:
                return Regex.Replace(PhoneNumber, @"(\d{3})(\d{3})(\d{4})", "($1) $2-$3");
            case 11:
                return Regex.Replace(PhoneNumber, @"(\d{1})(\d{3})(\d{3})(\d{4})", "$1-$2-$3-$4");
            default:
                return PhoneNumber;
        }
    }
}