Shared Line Appearance has been added as a feature in Skype for Business Server 2015 CU1. For more information check out the following content on TechNet:
Plan for SLA in SfB: https://technet.microsoft.com/EN-US/library/mt612810.aspx
Deploy SLA in SfB:https://technet.microsoft.com/EN-US/library/mt612811.aspx
Sfb Cmdlet Index: https://technet.microsoft.com/en-us/library/gg398867.aspx
What is a quick update? Click here to learn more: http://aka.ms/NeptuneQuickUpdate