The term 'Reverse Look up' is used when you already have somebody's cell number and now you want to find out the owner of that number.
A reverse phone lookup will give you information like the Name, Age and Address of the owner of that telephone number.
The commonest reasons why people want to trace somebody's mobile number are as following.

• People want to find out who their spouse is talking to
• People want to find out who that prank caller was
• People that want to check on who their teenage children are talking to

White pages won't work for cell numbers - as you may probably already know, the white pages only list residential land numbers.
Neither the white pages, nor any other free public telephone directory lists cellular numbers.
This is because wireless numbers are considered 'private' (in contrast to land numbers) and they are even protected by certain privacy laws like the 'Wireless 411 Privacy Act'.
You have to depend on other online reverse databases maintained by private companies if you want a reverse look up done for mobile phone numbers.
Too many databases, which one do you choose? - Just like every other product or service, when it comes to tracing cellular numbers too there are a bunch or so called 'services' that are waiting to help you.
But are they all equally good and accurate? Not really! This is why it's really important that you consider the following three tips when selecting a service.

1. Size matters - if the database is smaller than 200 million numbers, you only have about a 60% chance of finding your number.
   Not worth wasting your time.
   
2. Accuracy matters - Need I say more?
3. How up-to-date is it? - As you know, people change their mobile numbers as they change plans and old numbers are given to new subscribers etc.
   So if the database you're using is not updated on a regular basis you are bound to get the name, age and address of a previous owner instead of the current owner that you're looking for