Reverse cell phone number directory has gained much popularity over the years simply because it promises instant information on owner of not only mobile, but also landline, business and unlisted numbers. While searches on landline, business and toll-free numbers can be done for free on the public domain, it is hardly the case for mobile and unlisted numbers due to the source of information. However, there are 3 things users need to be aware of before paying for any reverse cell phone number directory.