By using the suggestions below, you can store your phone numbers that users enter in strict numeric only format, with no additional characters, then display it in a standardized way. I've found this useful for visual purposes and for displaying numbers automatically that can be used by external applications as hyperlinks, like Skype and iPhone.

When entering the phone number in your DB through insert or update, I use the following REPLACE directly in the SQL to get rid of spaces and characters. Adjust as needed.

REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(@Phone,'x',''),',',''),'.',''),')',''),'(',''),'-',''),'','')

This formatter will display a number as (XXX)XXX-XXXX where [phone] is your db column name. You can play with it to adjust for your purpose.
{IIF,[FORMAT,[phone],{LENGTH}]>10,[FORMAT,[phone],{MID:0,{MATH,[FORMAT,[phone],{LENGTH}]-10}}],}{IIF,[FORMAT,[phone],{LENGTH}]>7,([FORMAT,[FORMAT,[phone],{RIGHT:10}],{MID:0,{MATH,[FORMAT,[FORMAT,[phone],{RIGHT:10}],{LENGTH}]-7}}]),}{IIF,[FORMAT,[phone],{LENGTH}]>4,[FORMAT,[FORMAT,[phone],{RIGHT:7}],{MID:0,{MATH,[FORMAT,[FORMAT,[phone],{RIGHT:7}],{LENGTH}]-4}}]-,}[FORMAT,[phone],{RIGHT:4}]