Teams external communication with skype for business and teams

Occasional Contributor

Hello Everyone, 


So I've recently been tasked with Migrating our business to Teams from Skype. 


I have successfully done this with no issues for internal users. But the only issue is with communicating with External Teams and Skype for Business Users. 


When communicating with external Skype for Business through teams. they appear as online, whereas teams users appear as offline on the skype for business side. this stops Skype ability to call and sometimes communicate with our teams users as they are classed as offline.


I have also noticed that Teams to External Teams users cannot call at all. and sometimes do not receive messages at all. 

If anyone has experienced the same issue, did anyone find a solution? 


11 Replies
As Adam said check your upgrade mode, what do you have it set for your Org and or individual users? Teams Only is required for Interop to work in Teams to Teams etc. and if you recently changed it, it can take many days for it to fully update on the back end for the interop routing to work.

@Chris Webb @adam deltinger 


I Have checked this, I have both admin panels in front of me, both have the Coexistence set to Islands and are enabled to communicate with Skype for Business. There must be another underlying issue, as they can communicate, but only call through teams initialising it.

Yeah your issue is islands. You have to be Teams only if you want external comms to work with Teams otherwise it’s all on the Skype side, same with presence etc. once you switch to teams only then your endpoint uses Teams to the rest of the world.

@Chris Webb 


Right okay, The teams to teams communication


So for now I'd like to focus on the ability to speak with skype as we have a lot of customers using skype for business still. Currently communicating via message works, but the teams side appears offline for the SfB user.

Because islands. What I Just said affect your internal with external too. If you are not on Teams Only. The other end is going to see your Skype for Business presence. Anything other than teams only and everything Skype for business related is going to point to Skype for business. If you want your presence to show to the outside world and you aren’t logged into S4B then you have to be in Teams Only.
Watch this video from this time on, or the whole thing as it's very well done around all coexistence. Anyway, the timestamp starts at federation, which you can see all target endpoints end up at S4B unless on Teams Only, same is true for Presence being sent.


@Chris Webb 


Thanks for your help, this solved my issue.




@Chris Webb Can I continue on this topic?


We work together with a partner for several projects. I have a different experience with 2 users of this partner. Our teant is in "Teams only". The other tenant is "Islands". But both users of the other tenant are in "Teams only".

As you can see in the images, you see that one user gives the notification that he"s from outside our tenant, the other is not giving any notification. I see also a difference in the color of the top bar.

How can this be explained?scapta2.jpgscapta1.jpg

Sure. One user is connected using ‘search externally for’ or what they consider federation.

The other is most likely a guest in a team on your tenant so it’s chatting direct with the user in your tenant.

You can verify by typing in their full address. You will see the guest account on top then an option to search externally which will use federation if you choose that.

The difference in their end is if you use the guest account to chat it’s full fidelity but they must switch tenants to chat.

External chat to Teams users are minimal features currently but a new 2 federation chat is coming to enable more features with teams fed users.

@IzJordan  Hello do you want to chat?

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