Step by Step Guide on how to Configure UCS with Skype for Business Server 2015
When Skype for Business Server 2015 and Exchange 2013 are deployed together, user contact lists can be stored on Exchange 2013 and called using EWS instead of SIP requests to the Skype for Business Server. By default, contact lists are stored in Skype for Business’s SQL database.
Enabling the UCS allows users to work with a single contact list across all the Microsoft Office applications.
The pre-requisites to enable the Unified Contact Store (UCS) are:
Exchange 2013 CU1 installed and configured
Skype for Business Server 2015 or Lync Server 2013 configured
Ensure server-to-server authentication is in place using the OAuthTokenIssuer Certificate
(check another post of mine here)
By default, there is only one CsUserServicesPolicy; the Global policy. This controls whether UCS is enabled or not
If you want granular control of this setting to users, you will need to create other policies using the New-CsUserServicesPolicy cmdlet and set the UcsAllowed parameter to $True. This level of control allows application at the global, site, or the per-user scope allowing administrators to configure users to store contacts in either SQL or Exchange 2013. This command will disable the CsUserServicesPolicy Global UcsAllowed parameter, perhaps something that should be done before even contemplating this feature:
Set-CsUserServicesPolicy –Identity Global –UcsAllowed $False