Consider the following scenario:
Microsoft Skype for Business Server 2015 is integrated with Microsoft Exchange Unified Messaging (UM). Both user A and user B are UM-enabled.
User A sends user B an email message that contains Japanese characters in the subject.
User B receives the email message, and then moves the mouse point over user A.
User B makes a call to user A from the drop-down list next to the phone icon.
User A doesn't answer the call and receives a missed call notification email message.
In this scenario, Japanese characters in the subject line of the missed call notification email message are garbled.
This issue occurs because the user notification XML file that's sent by Skype for Business Server is encoded by using US-ASCII instead of UTF8.
To fix this issue, install the November 2016 cumulative update 6.0.9319.272 for Skype for Business Server 2015, Front End server and Edge server.