When this issue occurs, localized text strings that are not in English will not be updated to new text strings as KB 3064068describes.
Note The description text for the "Join Skype Meeting" link will be updated to "This is an online meeting for Skype for Business, the professional meeting and communications app formerly known as Lync." However, it is not displayed in the localized language.
Refer to the following screen shot:
A resolution for this issue is scheduled for a future update for Skype for Business.
Note Microsoft Lync 2013 was upgraded to Skype for Business in April 2015.
Get the May 12, 2015, security update 3039779 for Skype for Business (Lync 2013).