Many classified websites would like to give their users the possibility to hide their real phone number. In this case they can use the DNA API in order to associate on the fly a Toll Free or a Premium number to phone number of the user.
In this case the classified web site can offer a service for free to the users and be rewarded via the Premium Calls (if they choose the premium number option)
PREMIUM VOICE LINK
There are more and more telephone directories on the WEB that show up on the top positions of the search engines and are driving a lot of traffic.
In order to monetize this traffic the geographic numbers are replaced with Premium Numbers with low cost per minute.