Example 5: Key in a telephone number (menu item 2)

In the previous examples you created an application which received an incoming call and presented a menu to the caller. In this example you will add functionality to the second menu item so that the caller can key in a six digit telephone number that must begin with a 2. The example introduces the use of the Call object to get a sequence of DTMFs from the caller, and the use of the InputValidator interface to validate the caller's input.