If someone gives you their cell phone number, don't lose it. Your cell phone applications include a cell phone directory for you to store cell phone numbers in your phone. While there are other ways to find a cell phone number, this provides the easiest way.

Phone books do not publish cell phone numbers, and online cell phone directories only list cell phone numbers at the request or with the permission of the cell phone owner. However, it is still possible to do a cell phone number search online.

Cell phone users, in general, want to keep their numbers private. Keep the following information in mind when you consider using a cell phone number directory:

1. According to US government regulation, telemarketers with automated dialers cannot call cell phone numbers.

2. There is no national cell phone do-not-call registry in the US, and efforts to create a privately-funded cell phone directory or 411 services have failed.

3. The national do-not-call registry does not regulate business-to-business calls.

Action Steps
The best contacts and resources to help you get it done

Find a person's cell phone number with an online cell phone directory

Many individuals list their contact information in online cell phone directories. Enter a person's name into the search field on these websites to request their cell phone number. Some sites provide free service, while others charge a fee.

I recommend: Supply the person's name and location at MobilePhoneNumber.com to find out if the person is in their database. It provides a link to a pay service where you can get more information if the do not have the cell phone number. Search by name or phone number at Cell Phone Directory.

Identify the caller using a reverse cell phone number lookup

Some companies provide reverse cell phone directories, designed to identify the caller by the cell phone number. If you receive calls from an unknown number, enter the number to get the owner's information.

I recommend: PeopleLookup provides reverse cell phone searches to find the owner’s name. Search for the unknown caller using the "Cell Phone Caller ID" at addresses.com, where you can also search for a person's email address and alternative contact information in the yellow or white pages.

Hire websites to find important cell phone numbers

Businesses can obtain information, including cell phone numbers, using people search websites that employ private investigators and offer professional, confidential services.

I recommend: Hire professional investigators to find a cell phone number at Best People Search. An assigned investigator from iinforsearch.com will find a person's cell phone number and includes international cell phone numbers.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Look for the cell phone number of someone who previously called your cell phone in your cell phone itself; most cell phones keep a temporary list of received calls, making it easy to call people back.