This feature has been available on most portals for years, more commonly called "People Finders" or "People Search". If your number is published, it's freely available to anyone. You don't even need a number, just a name. Go into People Search on Yahoo. Type in your name. Go into advanced. Click search. There you will find your name, even your age. I can pay $50 and get every piece of information on you if I know your name and city. We live in an information society, there is very little you can do to hide. Your personal information is available to anyone who seeks it.