I agree with William. I opened Contacts after upgrading to Mavericks and found that all the hyphens and parentheses in my phone numbers had been removed. WHY? Apparently, the "geniuses" at Apple don't know the purpose of breaking up numbers with hyphens or dashes. They are easier to use and remember for the human brain. There's research supporting that. Obviously, the concern of Apple is to make things easier for its applications and its programmers. Their needs come before the needs of the consumer or end user.
Please enable us to format our contact numbers!!!!