What are the benefits of an online phone directory?

I have also provided a link to a website that provides telephone directoty systems. Please referencet them for specifics on what a telephone directory system can provide. If I am "reading" the question correctly, you are asking about the benefit of dial by name directories on a PBX system. The central benefit of any system like this is twofold. First, if you have a large business, having a dial by name directory can help any caller track down the correct party. If you have a small business, the directory system makes your organization look larger.