By far the best and easiest source for finding residential phone numbers is the phone book. Fortunately, you no longer have to wade through a mighty directory to find the number you're looking for. Today, most phone books are available free of charge online. Google has discontinued its phone book feature, but you can use its search function to track down residential phone numbers that have been posted on the web.

Whitepages has the largest database of residential phone records in the United States, so if the person's number is listed, you'll probably find it here. To run a free search, navigate to the Whitepages.com home page and type in the person's name and state. Results will come back instantly, including the person's phone number and address.

Zabasearch claims to have three times more residential listings than Whitepages so, if you can't find a phone number on Whitepages, you may get a match here. Simply pop the person's name into the search bar to get a name and address. Like most people-related search engines, Zaba offers both free and subscription services. Residential landline numbers usually turn up in a free search, but you might have to pay for a deep dive into unlisted numbers and cellphone numbers.

If the person you're trying to contact has ever given his number on the web, then a simple Google search should find it. Just type the person's name into Google's search field to see what turns up. Remember to use advanced search techniques like enclosing the person's name in quotation marks, which can help eliminate irrelevant results. If the person is connected with a specific website or organization, you can use Google to search solely within that site. For example, entering Facebook.com "John Smith" will reveal whether John Smith has linked a telephone number to his Facebook profile.

If your other searches are drawing blanks, head over to Pipl. This people-related search engine claims to search the "invisible web" to find residential phone numbers, including sources like personal blog sites, databases and paywalled webpages that other search engines cannot read. If the person has posted her phone number anywhere on the web, including an unlisted number, Pipl should find it. Search by typing the person's first name, last name and city into the search function. Results come back as an easy-to-read profile which includes the person's photo, so you can quickly verify that you have found the right person's number.