Reverse lookup is performed on the Internet everyday, with some fifty thousand searches or more.
However, the big question is, why do people bother looking up both landline and mobile numbers? Here are some of the most common reasons: 

• To link a name to a number that's not on their contacts list
• To apprehend crank callers
• To hide from persistent bill collectors
• To check on and confirm a spouse's infidelity
• To look into who the kids are talking to

So what's the easiest way to do this? In order to secure Privacy Rights, public phone books do not carry mobile numbers, so they are only useful for landline lookups.
If you have a lot of cash (a few hundred dollars or more) and can wait a few days for the information, you can hire the services of a private investigator.
But first you have to find a detective, and it also doesn't have a lot of confidentiality.
Actually, this was part of the past and hardly anybody nowadays use private investigators for this job.
Online Reverse Mobile Phone Lookup - the easy button! Not only is it the easy button, it is also your only option when it comes to searching a mobile number.
Even for a land number, these services give you tons more information than just the white pages does.
The other advantages of these online directories are;

• You can be assured of your confidentiality - nobody will find out about your investigations
• You don't have to step out of the house to get the information you need.
  
• Just a few clicks of your computer's mouse, and the information will be with you within a couple of minutes
• You can perform an unlimited number of searches