Teams only default co-existence mode in a SfB hybrid scenario.

Jorgenson, Brian E 1 Reputation point

Our company is in the process of migrating SfB on-premise users to Teams only mode with a completion date of approx March 2021. We currently have a SfB 2015 farm setup in a hybrid configuration with Skype Online. Our current Skype/Teams online co-existence mode is Islands.

While we migrate existing users to Teams only mode, I would like all new users to automatically be configured in Teams as Teams only mode once they are assigned an O365 license, so we don't have to set them up in SfB on prem.

All of our Skype Online users have been converted to Teams only mode so we only have SfB on prem users and Teams only mode users.

If I set our Teams organizational default config from Islands to Teams only mode, does this affect current SfB on prem users? Does this affect existing Teams only mode users from communicating with SfB on prem users and vice versa? If I set our org config to Teams only mode, can I easily set it back to Islands mode if we run into any issues?

Microsoft Teams
Microsoft Teams
A Microsoft customizable chat-based workspace.
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Skype for Business
Skype for Business
A Microsoft communications service that provides communications capabilities across presence, instant messaging, audio/video calling, and an online meeting experience that includes audio, video, and web conferencing.
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  1. JimmyYang-MSFT 49,886 Reputation points Microsoft Vendor

    Hi @Jorgenson, Brian E ,
    It will affect Skype for Business on prem users communicate with Teams users when you set Teams organizational default config from Islands to Teams only mode. The following table show that you can only use Microsoft Teams to chat each other.


    You can change the upgrade options for all user at any time in Teams admin center. For more reference:

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