public static void Main()
PhoneCustomer phoneCust = new PhoneCustomer();
phoneCust.CustomerID = 123;
phoneCust.FirstName = "Joe";
phoneCust.LastName = "Smith";
Console.WriteLine("{0} {1} {2}", phoneCust.CustomerID, phoneCust.FirstName, phoneCust.LastName);
Console.WriteLine(phoneCust.UpperCaseLastName("Mr."));
public const string DayOfSendingBill = "Monday";
return string.Format("{0} {1}", prefix, this.LastName.ToUpper());