I can using "\*" as valid input.
However, how to using "#" as valid input with Form Element?
Please guide me to solve this problem.......
You need to set a VXML property to redefine the termination character (termchar) which is, by default, the pound sign. Typically you do this on the application as a whole, although you can be more specific and do it on the element and redefine it on the next element.
You can set it to nothing - use space in quotes.