An ex-directory, or unlisted phone number, is a number that doesn't appear in the phone directory. This is usually because the owner of the phone number has chosen not to appear in the directory; they may have been required to pay a fee to remain anonymous. If you want to contact someone who has an ex-directory number, you'll want to employ a little detective work in uncovering the telephone number.
Use a search engine to look for the person's name. Sometimes an unlisted phone number will find its way into one of the online phone directories.
Gather information about the person you are trying to find a phone number for. For example, schools attended, street address, friends and relatives names.
Contact the person's friends and relatives and ask them for the phone number.
Search social networking sites like Facebook, MySpace or Classmates for the person (or their friends and relatives).
Pay for a phone number search service. There are many sites to choose from, including People Finders and Intellius, who will perform a free search but you'll have to pay to get the actual number (which may be a listed number) . In the United Kingdom, try Telephone Number Search: they charge a fee of £4.99 and up (as of July 2010) for a single search.
The more information you have about a person, the more likely you are to be able to find their number. For example, if you are looking for a woman and you know she has remarried, you may be able to find her number under her married name.