The first question that should be addresses is why would someone want to find a cell phone number? Finding means searching obviously and I can think of a few reasons why this might be useful. The first and foremost is to discover the identity of someone. If you only got a person's cell phone number you might be inclined to find the name and other information before making a call.
This can be useful if someone called whose cell phone number is unknown. It can be also useful to check out old cell phone numbers that someone wrote down without adding a name to it, you know, those cell phone numbers that one gets in certain bars for example. Would be embarrassing to call without knowing the name of the person you are calling.
The biggest problem to find a cell phone number is the fact that they are not added in the phone registry which means one has to rely on online services to find the information. Many sites charge for access to their databases but some provide the information freely.
Now the easiest way to find out the information you are looking for is to enter the phone number into Google and hope that Google has a record of it. That method is uncomplicated and free.
It the cell phone number you are looking for is not in the results you might run into a few troubles. Most sites advertise their service as free but either redirect to a paid service or ask you to pay after revealing some of the information you are looking for.
Everything else is does not seem worth the effort. I checked roughly 30 or so sites that promised a free look up only to find out that they did either sell membership directly or redirected you to membership sites.
Google is therefor your best choice to find a cell phone number followed by other search engines, the yellow- and whitepages plus social sites like Facebook and MySpace.
Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.