Raised when a user credential is requested by a server such as the Lync server.
Assembly: Microsoft.Lync.Model (in Microsoft.Lync.Model.dll)
This event is only raised when Lync client is in Full UI supression mode and a user has not provided acceptable sign-in credentials or other credential types requested by othe r servers. When not in UI suppression mode, this even is not raised when credentials are requested. In this case, the Lync client presents a credential request dialog.