An Active Directory contact name is not displayed but the phone number is displayed in Microsoft Skype for Business 2015 (Lync 2013). This issue occurs when the following conditions are true:
An Active Directory contact contains a telephone number, an email address, and a full name.
You have set the EnableExchangeContactSync parameter to False or cleared the Sync contact info between Skype for Business and Exchange option in the Personal section of Options.
This is caused by a missed scenario to fetch the contact's display name.
Article ID: 4051054 - Last Review: Nov 7, 2017 - Revision: 15