These directories specialize in certain geographical areas or they try to include a lot of additional features in the telephone directory to capture the slice of the market. The advertising agencies also have a number of telephone directories to advertise their products from. Besides providing off line services in the form of paper back directories coming in different colors like white, yellow, blue, grey, green etc, these telephone directory companies also provide the same facilities off line also to the customers. Provision of the free people search facilities and other services are provided by both online and offline to the customers. These directories are the most reliable contact information available for the users at large. Besides providing accurate information these companies allow the users to find people and connect with different people free of charge.