TextBox formatting is lost when focus changes

Question

I have a Windows form with a data-bound text box that displays a phone number generated as follows: [phone]. Data is saved as decimal and then displayed in the correct format. The problem is that when I click on the text box and then click on something else, it changes from [phone] back to 8005555555. Formation is lost. I tried changing the numbers again on the leaveBox event, but this will not work. What could be the reason for this?

vs 2010 C #

to format first i do this

private string FormatCustPhoneBox(string a)
{
            string phone = a;

            for (int j = 0; j < phone.Length; j++)
            {
                if (!Char.IsDigit(phone, j))
                {
                    phone = phone.Remove(j, 1);  //Remove any non numeric chars.
                    j--;
                }
            }
            return phone;
}

then i do it

    private void FormatPhoneNum()
    {
        decimal iPhone = decimal.Parse(CustomerPhone1Box.Text);
        CustomerPhone1Box.Text = string.Format("{0:(###) ###-####}", iPhone);
    }

Answer 1

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