Assume that you create a contact in Microsoft Outlook. The contact has Business Phone number, Home Phone number, Mobile phone number, and the email address and is stored in Microsoft Exchange Server. Then, you search for the contact in Microsoft Lync 2013 (Skype for Business) and try to call the contact by selecting the Click-to-Call menu. In this situation, the phone numbers are not displayed for the contact. Therefore, you can't call the contact on these phone numbers. The Click-to-Call menu only displays the New Number and Skype for Business Call options.
This issue occurs because the Address Book Web Service cannot be contacted.