Skype for Business Server is Microsoft's on-premises chat, presence and conferencing server, now sold as Subscription Edition. Pages here cover replacing it with self-hosted Mattermost, Matrix with Element and Jitsi.
For on-premises Skype for Business estates choosing a chat platform that stays in their datacenter: presence, IM and group chat against Mattermost channels, what Mattermost editions add (SSO, AD/LDAP sync, clustering), and what has to come from elsewhere, such as telephony and room systems.
Comparing Skype for Business Server with a Matrix homeserver and Element clients: chat and presence, federation with partner organizations, voice and video through Element Call, and Element Server Suite editions against Server/CAL subscription licensing.
A cutover plan from Skype for Business Server to Mattermost: syncing users and groups from Active Directory, re-creating persistent chat rooms as channels, moving meetings to a video service, retiring Edge servers and running both systems during the transition.
Moving from Skype for Business Server to a self-hosted Matrix homeserver: LDAP or SSO login, rooms for persistent chat, federation in place of Skype federation, Element Call or Jitsi for meetings, and the order in which to decommission front end and Edge servers.
Cost of ownership by component: SE server licenses and Standard, Enterprise and Plus CALs that must carry Software Assurance or be subscriptions, Windows and SQL Server underneath, against Element Server Suite or community Synapse, Jitsi servers and the people to run them.
For teams still on Skype for Business Server 2015 or 2019 after October 2025: the three real paths (Subscription Edition, Teams in Microsoft 365, or a self-hosted open-source stack), what each requires and how to choose when cloud is ruled out.
For disconnected and classified networks that ran Skype for Business on premises: chat, presence and meetings rebuilt with Mattermost Enterprise Advanced or Element Server Suite Sovereign plus Jitsi, and how updates and licensing work with no internet connection.
Replacing what the Enterprise CAL buys (audio, video and web conferencing with desktop sharing) with Jitsi Meet or BigBlueButton on your own servers, including SIP dial-in through Jigasi and how meeting links reach Outlook invites.
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