Have you ever been struggling with Teams and Skype for Business not cooperating? Or maybe your Teams messages are not being received externally? Maybe you are using Islands mode. Read on!

In this post I will introduce you to the Teams coexistence modes, which will probably lead you to the root cause of your issues (if any). You can find the modes switch within the Microsoft Teams admin center > Org-wide settings > Teams upgrade.

You will notice there are a few modes from which you can select:

  • Islands
  • Skype for Business only
  • Skype for Business with Teams collaboration
  • Skype for Business with Teams collaboration and meetings
  • Teams only

Note: If your Office 365 tenant got created a while ago (before November 2018) you will notice that Islands mode is setup by default. As the name already suggests, this mode will let Teams and Skype run as two independent systems. There is not really any connection between the two.
For example, when you send a message from a Teams client, it will be received on a Teams client. The same goes for Skype messages.

“So, what’s the deal with Islands mode?”

When your tenant is configured in Islands mode, no specific platform has been chosen as primary collaboration tool. This means that every user of your organization must be logged on to both clients (Skype and Teams) in order to be able to receive messages from Skype and Teams users.

Also, be aware that when it comes to federated messages (from people outside your tenant), these kind of messages will only be received on a client that is able to handle Skype messages. This probably explains why you are not receiving messages from people outside of your organization, even when both users are using Teams as client.

Therefore, I advice you to make a choice for one of the other coexistence modes, preferably Teams only mode, regarding to the future of Skype. However, be aware this will impact user experience since they will be unable to create Skype meetings from Outlook any more.

Don’t forget about user acceptance and adoption, especially when users are heavily depending on Skype!

“We’re not ready for Teams yet!

No problem! If your organization is not yet ready to adopt Teams, you can consider selecting another option, for example Skype for Business with Teams collaboration. Due to readability and length of this post I will not explain all of these modes.

Last but not least, Microsoft did a really good job explaining all of the coexistence modes on the following page:


I hope this post will help you understand the interoperability between Skype and Teams, and to take next steps in enrolling Teams within your organisation.

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