Traditional phone directories are not applicable when looking for customer information given the phone number.
There are lots of available methods nowadays to search a name by a cell number.
The first method is to use search engines.
People who frequently receive anonymous calls can type the cell number in any search engine and do an online search.
Chances are they will find basic information about the owner of the number.
However, this is not as reliable as the other methods because not all results are being verified before displaying publicly.
The next method to search a name by cell number is to look in volunteer directories.
They contain personal information voluntarily given by phone users.
Similar with search engines, not all information are accurate and reliable.
This is because such directories do not have adequate facilities to confirm if the user-supplied data is true or not, and chances of having bogus volunteers are high.
Free reverse lookup directories are also applicable to know the identity of unknown callers.
It can provide the needed information at times but not in all cases.
What they do is to simply offer a search utility to crawl in every public domain that has phone number records.
This method can only offer minimal information or even none at all for each query.
The last possible option to search name by cell number is to avail paid subscriptions in a reverse lookup directory.
They have a diverse database entries legally collected from public domains, government records, telecommunications companies, and other institutions to provide higher chances of acquiring useful results like name, address, police records, and so on.
The drawback is that monthly and subscription fees are impractical for customers who will only do a one-time search.