Exchange Unified Messaging (Planning Tool)
Skype for Business Server 2015 supports integration with Exchange Unified Messaging (UM) for combining voice messaging and email messaging into a single messaging infrastructure.
For details, see:
"Unified Messaging" at https://go.microsoft.com/fwlink/?LinkId=285341
"Planning for Unified Messaging" at https://go.microsoft.com/fwlink/?LinkId=285344.