Since Microsoft Teams and Skype for Business Online have some overlapping functionality (chat, calling, meetings), Microsoft provides a couple of ways to manage the migration to Microsoft Teams, as well as the interoperability with legacy Lync/Skype for Business. This is managed through coexistence modes determined by a TeamsUpgradePolicy. Assigning a coexistence mode to a user or the tenant will determine how incoming calls and chats are routed, as well as where users can schedule their meetings.
The first coexistence mode is Islands. This mode treats Skype for Business and Microsoft Teams like they are two separate products. The end user can use all functionality in both products, such as calling, chatting, and scheduling meetings. An incoming call from other Teams or Skype for Business users will land in the end user’s same client. Inside of Teams, the user will have access to teams and channel functionality. This is usually a good coexistence mode to start with if the end user can understand the difference between the products and can handle having the same functionality in both. Starting in this mode can drive Team adoption more quickly.
The next mode is Skype for Business Only. All incoming calls and chat messages are routed to Skype for Business, where the user can schedule meetings. However, this mode is not currently enforced, as it will not remove any access to Teams for Teams and channels access.
Next is Teams Only mode. As its name suggests, the end user will use only Teams for calling, chatting, and scheduling meetings. When this mode is applied, the user is considered upgraded to Teams, as they will no longer use Skype for Business. However, this mode does not prevent the end user from joining Skype for Business meetings, as they may still receive invitations from coworkers or external partners. There is also an option in the admin portal that will determine if the user can join these meetings via the Skype desktop client or the Skype meetings app.
The last two modes are currently not available in the admin portal, as they do not yet have the components in the service to be enforced. The first is Skype for Business with Teams collaboration. As the name suggests, Skype for Business with Teams collaboration will give Skype for Business chatting, calling, and meeting scheduling abilities while Teams is only available with teams and channels.
Users will not have the ability to use Teams for calling, chatting, or scheduling meetings, and these options will be removed in the Teams client. If the overlapping functionality of calling and chatting with the two clients might confuse your users, this would be a good mode to start with, as it will distinguish each client with only certain capabilities, without overlap. The concepts of teams and channels can be explored in Teams without worrying about chatting, calling, and meetings.
The second currently unavailable mode is Skype for Business with Teams Collaboration and Meetings, and it takes the previous mode a step further by moving the ability to schedule meetings to Teams. This gives the user a first-class meeting experience in the Teams client, while still using Skype for Business for chatting and calling. Each client is still only responsible for specific tasks without any overlap between the two. Chat is available in the Teams client, but only during meetings, and is not available for 1-to-1 chats.
To clear up what how each mode works, here is a visual diagram that shows each mode and the capabilities provided by each client.
Coexistence modes are applicable for both users homed in Skype for Business Online and on-premises or hybrid scenarios. However, in order to move to Teams Only mode, the user’s corresponding Skype for Business account must be homed into Skype for Business Online. When using one of the other coexistence modes, there are also other advantages to having the Skype for Business account already in Office 365 in relation to interop and federation, but that is a topic for a different article.
So how are these modes managed? In the modern Microsoft Teams & Skype for Business Admin Center (https://admin.teams.microsoft.com), navigate to Org-wide settings > Teams upgrade. Here you can control settings for the entire tenant, and options may vary from tenant to tenant depending on where they are in the feature release cycle. First, there is the coexistence modes drop-down menu, and whether you want to notify users that an upgrade to Teams is coming. This upgrade notification feature is displayed in the Skype for Business client when they log in. Notice the only options in the admin center for modes are Islands, Skype for Business Only, and Teams Only. As previously mentioned, the other two are not available yet.
Other options include app preferences, such as you want users to join Skype for Business meetings once they move to Teams Only mode. They can use either their existing Skype for Business client to join meetings, or use the Skype Meetings App if the desktop client has been removed.
Finally, if you are preparing end users for Teams Only mode, you can prepare Windows-based systems to download the Teams client in the background in preparation for migration.
While the above sets the coexistence mode for everyone in the tenant, you can set the mode on a per user basis. This allows migrating cohorts of users from one mode to another. In the admin center, navigate to Users and search or select the user to modify. In the user account options, there is a section for the Teams upgrade mode and whether you want to notify the user that a change is upcoming.
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As mentioned previously, there are advantages to having the Skype for Business account already homed in Office 365 when using coexistence modes. However, sometimes there are situations when you need to keep the account in your on-premises environment. Fortunately, this is not going to prevent you from using the modern Teams meeting experience. Announced at Microsoft Ignite 2018, there will be a future capability where on-premises users can take advantage of Microsoft Teams meetings. For more information, check out BRK3124 – How Skype for Business on-premises customers can take advantage of Microsoft Teams meetings.