The dial only works when a contact is showing from within the contacts folder. There is an option to find contacts using the search in the home screen from email ribbon and this shows a pop up with the contact details. There is a phone icon but this is greayed out. This is a very useful feature of Outlook that means users do not need to go to contact to call them, email them etc. You should support this feature to be fully compliant with Outlook 2016.