Version: Skype for Business 2015 on premise
Windows installations
Skype should be connected to your Active Directory
→ Windows login equates Skype login
Connection to Skype for Business is established via UCWA. Refer to MS docs on ucwa.
Currently a single Authentication Method IWA (Integrated Windows Authentication) is implemented. Refer to https://msdn.microsoft.com/en-us/skype/websdk/docs/developforskypeforbusiness#sectionSection2.
Skype and Confluence should be able to communicate via CORS. This means the following header must be set in your Skype server:
Access-Control-Allow-Origin: your-confluence-server.com