You no longer have to worry about unidentified people calling you.
Reverse lookup is here to help you reveal identity of all such callers.
You can even retrieve personal data and address of the caller.
Why do you need reverse lookup?

• Popularity and easy accessibility of such service will definitely discourage pranksters.
  All those threatening calls made with evil intentions can be stopped now.
  You can easily trace their origin and reveal identity of those people who resort to such pranks.
  
• A reverse lookup has other benefits too.
  Your child's safety can be ensured by it.
  By going through call history of your child's cell phone you can identify callers and trace their identity.
  As a youngster, your child may not realize the danger of talking to unknown people but you, as a responsible parent can save him from future danger.
  
• If you have missed a call or do not recognize the number from which calls have been made to your number, you can use reverse lookup to identify the number.
  Then you can decide whether to call back or accept calls from that number in future.
  
• If you are burdened by suspicion against your spouse, a reverse lookup can reveal the details of people who are making calls to your partner.
  You can perform investigation on your own, without involving anyone and get the details.
  A little effort can either save your marriage or you from being cheated.
  
• Even a busy businessman can use this service.
  You will not miss a single business call as the details of all calls from unknown numbers can be traced back.
  

But if you access a free site then the results will be limited.
Seldom has a free site provided relevant data.
Their database is very limited and often is not updated on a regular basis.
So if you require fast result with authentic and up to date data then paid service is the answer for you.
Against a nominal charge you will receive data that you require and can identify the callers for whatever reasons may be.