Microsoft fully supports hybrid organizations with a mix of TeamsOnly users and on-premises Skype for Business users.

Hybrid organizations need not move their on-premises Skype for Business users to the cloud as a result of this retirement. In addition, Microsoft is providing assisted upgrades to help automate the upgrade of remaining Skype for Business Online users to TeamsOnly mode. Any online users must be assigned TeamsOnly mode using TeamsUpgradePolicy. However, hybrid customers with a mix of users homed online and on-premises must upgrade any online users to be TeamsOnly. The retirement of Skype for Business Online does not affect support for on-premises deployments of Skype for Business Server and Lync Server 2013. This article contains guidance for organizations with TeamsOnly users that were upgraded from any version of Skype for Business. In addition, beginning in October 2022, Microsoft will begin decommissioning aspects of that infrastructure specific to hybrid organizations.

Microsoft will begin decommissioning the Skype for Business Online infrastructure on or after June 30, 2022. For background on why Skype for Business Online was retired, see FAQ-Upgrading from Skype for Business to Microsoft Teams. The Skype consumer service isn't affected by this retirement. With Skype for Business Online being retired, Microsoft wants to ensure customers have the required information and resources to plan and execute a successful upgrade to Teams. Teams is the core app for communication and collaboration in Microsoft 365. This retirement was announced in July 2019 to give customers two years advance notice to plan their upgrades to Microsoft Teams. On July 31, 2021, Microsoft retired Skype for Business Online.

Skype for business admin center