Federation Between Skype for Business and Skype
Federation enables users between two platforms to add each other as contacts, exchange instant messages and make audio calls. Federation is available to other companies running Skype for Business (or earlier versions of Microsoft’s instant messaging solution including Skype for Business and Office Communications Server) and it is also possible to federate to Microsoft’s consumer instant messaging platform, Skype.
When federating between Skype for Business and the consumer version of Skype, users on each side simply add a contact using the username of the person they wish to communicate with. Skype for Business usernames usually match the user’s email address. Skype usernames are associated with a Microsoft account that may or may not match their username.