IM is only one portion of the Skype for Business suite. Microsoft has published details of supported configuration for qualified vendors through Unified Communications Open Interoperability Program (UCOIP). By default, supported combinations include encrypted communications using SIP over TLS and SRTP as well as unencrypted SIP over TCP and RTP. The communicator client also uses HTTPS to connect with the web components server to download address books and expand distribution lists. The live meeting client uses Persistent Shared Object Model (PSOM) to download meeting content.

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.

Microsoft lync 2013 client