Microsoft Skype for Business Server uses Session Initiation Protocol (SIP) for signaling along with the SIMPLE extensions to SIP for IM and presence.
Federation can be configured either manually (where each partner manually configures the relevant edge servers in the other organization) or automatically (using the appropriate SRV records in the DNS). Skype for Business supports identity federation, enabling interoperability with other corporate IM networks. mobile or home workers) as well as users in partner companies. Skype for Business Server also supports remote users, both corporate users on the Internet (e.g. Skype for Business Server uses Interactive Connectivity Establishment for NAT traversal and TLS encryption to enable secure voice and video both inside and outside the corporate network. This includes support for rich presence information, file transfer and voice and video communication. One basic use of Skype for Business Server is instant messaging (IM) and presence within a single organization.
