Here are the few ways to find the owner of a phone number:

1-The Cell Phone Registry:
This website is a very good website which provides details about phone number online. It has databases of mobile, landline and some other numbers. They can give a user an up-to-date data for you.

2-Reserve Directory:
You can find the basic information such as name and address of the phone owner. This site also includes some business and reverse phone search.

1-Finding the information about number who is calling you
2-Just for fun
3- Knowing who is making unfamiliar calls
4-Concerning positive aspects
5-Knowing who are you dealing with