c# winform 전화번호

        public string PhoneNumber(string pPhone)
        {
            string b = "";
            if (pPhone.Length == 9)
                b = pPhone.Substring(0, 2) + "-" + pPhone.Substring(2, 3) + "-" + pPhone.Substring(5, 4);
            else if (pPhone.Length == 10)
            {
                if (pPhone.Substring(0, 2) == "02")
                    b = pPhone.Substring(0, 2) + "-" + pPhone.Substring(2, 4) + "-" + pPhone.Substring(6, 4);
                else
                    b = pPhone.Substring(0, 3) + "-" + pPhone.Substring(3, 3) + "-" + pPhone.Substring(6, 4);
            }
            else if (pPhone.Length == 11)
                b = pPhone.Substring(0, 3) + "-" + pPhone.Substring(3, 4) + "-" + pPhone.Substring(7, 4);
            else if (pPhone.Length == 12)
                b = pPhone.Substring(0, 4) + "-" + pPhone.Substring(4, 4) + "-" + pPhone.Substring(8, 4);
            else
                b = pPhone;
            return b;
        }