There are millions of people that use cell phones now, and a large percentage of them use them as their primary phone. Probably, you are getting anonymous calls, or want to check who your significant other secretly talks to.
And you don't even need to know the person's name or in which city or county they live. However, if you are dealing with such matters, these can be very important indeed. There is a phone number search, all you do is enter the phone number, starting with the area code and seven digit phone number.
These websites naturally have to pay for access to some of this information, and go to the considerable trouble of pulling all the various resources together in one place. You might discover that the reverse lookup service also finds results for unlisted, unpublished or cellular numbers. You might discover that the reverse lookup service also finds results for unlisted, unpublished or cellular numbers.
Paid services can provide you many advantages. Free directories don't cover cell phone numbers, it is that simple.