Where Telephone Directories are Online
One of the best online directories is the one that you have in a paper version in your home, but it is the new and improved version. You can log on any time you want and use the white page or yellow page listings. You can search for someone by name, or you can search out a business by name or category in the same way you would with a paper book. Even better, the listings are national, which is not the case with your local book.
What is even better about these online yellow and white pages is that you can search for a number, but you can do so much more. If you have an unknown phone number coming up on your caller ID, you can do what is called a reverse phone lookup. They have the option right on the front page. You would enter the number to see if a match appears. This only works for listed landlines, but it is quite helpful if that is the case.
While you would not consider other sites as phone directories, some can be used as such. The search engines offer a wealth of information, and they can come up with some phone numbers as well. It all depends on the number being online though. These can not find what is not there. You should also consider sites like FaceBook as pseudo-directories as well. People entire their numbers there all of the time. It never hurts to search through to see what comes up.
You may want to use a reverse search like the one on the white pages, but the number in question comes up with no name or listing. If that happens, you have an unlisted landline, or you have a mobile number. You don´t have to give up. You can find this type of information through a reverse cell phone directory search. These help when no other tools are working out.