If you need to find someone's phone number or contact information you can use Outlook Address Book to search the company directory.

In Outlook you will click on "Address Book"

To get the MOST updated data you will want to switch from your local Offline copy to the Cloud based version of the Address Book (in yellow),  In the Search field (in blue) you can search by name or title, department, etc.  Or you can go to Advanced Find (in green).  

With Advanced Search you can search for multiple fields at once such as this example of finding purchasing dept at Time Manufacturing.

With the results like this:

Then you can open one of them to get the details on various tabs that you might need: