These services make sense for a whole lot of reasons. For instance a particular number might keep popping up on your spouse's cell phone or you might be the habitual victim of a prankster who keeps sending you odd text messages or making disturbing calls. Regardless of the nature of your concerns, you can always find what you need using such services.
More than 50% of the numbers in existence are either unlisted numbers or they come from cell phones, looking in a phonebook won't help at all because these records are not publicly available, they are part of the records of private cell phone companies.
Businesses exist that pay a lot for the opportunity to access records for unlisted phone numbers as well as cell phone numbers. This information that is gathered is then used to create very comprehensive databases that you can use to search for the needed information. This is because they spend money to get these databases together, they also tend to charge a fee for providing services such as reverse cell number lookup. Their fees aren't exorbitant but they are well worth what you pay for them.
Reverse cell phone number search services allow you instant access to records such as name, address and current location for just a small amount of money. All you need to have is the person's phone number and a credit card to sign up for the service in question.
Some people prefer to save money by using services that offer the chance to perform a one-time search, while other people who feel they will be using these services much more frequently prefer to pay a substantially larger fee.
You'd be surprised about just how much you can find out about a person just from their phone number alone.
To find a person's address using their cell phone number, go to http://www.cellreversesearch.com