Triming to all Numeric

Question>
I have a phone number that has all kinds of special characters or alpha characters that can be mixed up in the field

I want to trim all of the non numeric characters out of the field

Anyone have any ideas as to how I can do this with out creating many stage variables to do the trim?

Answer>
StripWhiteSpace(Convert("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-.", Space(56), Input.String))

If you have extra characters, just increment the number of spaces as needed.