For many years, it has been possible to perform a reverse look up for land line phone numbers on the Web.  If you simply key in a phone number (for a listed phone), you will get a listing of the name and address of the holder of that phone number.  That service was not available for many years for reverse cell look up.  A great Web site called lookupcell.net has filled that gap and now makes the service available for cell numbers.  Unlike most similar sites, this one will verify that a number is found before it asks the customer for any payment.