Symptoms
Assume that you enable Remote Call Control (RCC) feature in Microsoft Skype for Business Server 2015. When you sign out Skype for Business 2015 (Lync 2013), you receive a dialog box that says setting call forwarding settings failed.
Resolution
To fix this issue, install the August 1, 2017, update (KB4011046) for Skype for Business 2015 (Lync 2013).
Note Lync 2013 was upgraded to Skype for Business in April 2015.