This is an old revision of the document! Development Tips Seven Habits of Highly Effective Programmers Regular Expressions Phone number regex [\-.])))?[(]?(?<AreaCode>[\d]{3})[\-/)]?(?:[ ]+)?)?(?<Number>[a-zA-Z2-9][a-zA-Z0-9 \-.]{6,})(?:(?:[ ]+|[xX]|(i:ext[\.]?)){1,2}(?<Ext>[\d]{1,5}))?$}