If phone numbers can be searched in phone book directories, cell phone numbers can be likely found in a cell phone directory. However, directories containing list of cell numbers is not as many as those containing landline numbers; in fact they are quite limited. Also, most of the lookup services that update and list cell numbers are not offered for free. If the number you need to find is not in the white pages or in public listings, then you need to use the reverse phone service. This is generally a specialized lookup service, which can be availed by purchasing the access to the subscriber database of major phone companies and mobile operators. The reverse look up database practically contains almost all the numbers of people in the US, from landline numbers, unlisted numbers and cellphone numbers.

Companies offering reverse phone lookup services are prohibited to give out information for free. This is because they are bound by a privacy agreement with major phone companies. To protect the privacy of the subscriber, someone who is in search for the contact information of a loved one, friend or a client must pay a fee in order to obtain the information that they are seeking. Payments are usually made via credit card or paypal. The main reason why contact numbers are not given for free is to ascertain that the information won’t be used illegally and most importantly to protect the subscriber’s privacy.