User Configuration > Administrative Templates > Microsoft Office 2016 > Contact Card
User
HKCU\software\policies\microsoft\office\16.0\common\im
This policy setting allows you to remove the telephone option from the Contact Card and Outlook Ribbon. If you enable this policy setting, the telephone option does not appear in the Contact Card. Telephone links do not appear in the Contact Card. Telephone options do not appear in the Outlook Ribbon. If you disable or do not configure this policy setting telephone options appear in the Contact Card and Outlook Ribbon.