Instructions
Jump to: B) Make a call to a contact
A) Make a call to a phone number
A1) From the main Skype for Business window, open the "Phone" tab (dial pad icon).
A2) Type the number that you wish to call either using the dial pad buttons or using your keyboard. Then, click Call.
B) Make a call to a contact
You can start a phone call with one simple click. In your Contacts list or search results, place the mouse cursor over the picture (or picture display area) of the person, and then click the "Call" button.
Outcome
The call will be placed through your Skype for Business app.