Every organization needs a staff or employee address book to store employee contact details. This address book needs to be up-to-date and easy to find and use for all employees.
There are many ways to manage an organizational address book.
The simplest way is to create an a document or a spreadsheet that will contain a list of all employees and their contact information. Such document may contain contact information such as: office and mobile phone numbers, email address, office location, title, department and other
Once an address book document is created it can be placed at a network folder with read permission for everyone or sent via email to all employees.
File based organizational address book is the cheapest and simple way to setup an organizational address book but definitely not the most efficient one for the person in charge of updates, for the users and for the company.
A document based organizational phone book requires manual update, in most cases,  by a single person – probably the office administrator. That person will soon find out that constantly chasing after phone or office location of all employees is very frustrating task.
Employees who need to use the organization’s address book need to remember where on the network this file can be found. A common practice is to print all or parts of the address book every time it updates. These prints can accumulate to large numbers if every employee prints his copy of it and does that ever and over again whenever the address book updates.
In many organizations an email is sent whenever the address book is updated. These emails themselves are something that employees have to spend time on saving the attached file or printing it. Yes that is a waste of time by everyone.

More efficient ways to manage internal contact directory can be by using an intranet employee directory.
If you use a SharePoint you should read this great article by Patrick Luca on how to create a “who is who” application on SharePoint by importing user and contact information from Microsoft Active Directory
If your organization uses Oracle HR module to store employee information and contact details you may want to check Applaud’s Employee Directory.

That is if employees remember to notify the person in charge. Not only it is a real burden on the phonebook administrator, this phone book when updated is normaly sent by email to all employees. Most of them will spend time on such frequent emails and many of them will actually print every time an update phone book document is sent. This will cause many uneccasary prints.
A more efficient approach to organizational phone book would be such that allows self update. It is a good idea to allow users to update their own contact information.
Most organizations use Microsoft Active Directory as their network infrastructure. Corporate Directory is a great address book software for internal company use.
Corporate Directory brings user experience to a new level allowing them to find contact details of anyone in the organization in less than 1 second. It has the fastest search mechanism that shows result immediately as you start typing partial name, last name, title, department or phone number. It will display employee photos and will work even when you are offline.
Corporate Directory is a simple zero configuration install and it does not require a server.

You can download a fully working trial version here.

Having efficient organizational address book software can improve internal communication significantly. The ability of a person to browse the company directory, to see other people photos and their contact information makes personal communication easier and more open which is a key component of business productivity.

Many organizations use Microsoft Active Directory as their network infrastructure. Having that means that all the employees and others who need access to network resources have an account on the network database – the Microsoft Active Directory. Corporate Directory is the natural choice for organizational address book software that makes the task of search active directory easy, fast and intuitive. It removes administrative task overhead from the network system administrator of managing and updating Exchange contacts information attributes by allowing employees to update their own contact details back to the Microsoft Active Directory.

Softpedia guarantees that Corporate Directory 4.4.3.0 is 100% Clean, which means it does not contain any form of malware, including but not limited to: spyware, viruses, trojans and backdoors.

This software product was tested thoroughly and was found absolutely clean; therefore, it can be installed with no concern by any computer user. However, it should be noted that this product will be retested periodically and the award may be withdrawn, so you should check back occasionally and pay attention to the date of testing shown above.