As you may already be aware of, cell phone numbers are UNLISTED and therefore NOT available on free directories like the white pages. The following excerpt from Wikipedia explains the current standing on cell phone numbers.
"….In the US, under current rules and practices, mobile phone and Voice over IP listings are not included [...]

After researching SIX online services, the following service was the best by far with regard to the database size, accuracy and frequency of updating!
Use the search form below to find the owner’s name, address and other details of any cell phone number.

Reverse Telephone Directory - The Best Service by Far
We have researched multiple reverse phone directories and the following is the best service we have come across by far with regard to the following factors.

Quantity of telephone numbers held by the database - 217 million households are covered
The accuracy of reverse telecommunications information
Frequency of updating their [...]