Symptoms
When Transport Neutral Encapsulation Format (TNEF) is disabled in Microsoft Exchange servers of both organizations, an online meeting is displayed as offline in Microsoft Skype for Business 2015 (Lync 2013).
Resolution
To fix this issue, install the January 3, 2017, update (KB3141468) for Skype for Business.Note Lync 2013 was upgraded to Skype for Business in April 2015.
