When Microsoft announced Teams native federation in Nov 2019, I was pretty excited and was under impression that, Microsoft Teams is going to support federation (MS is mentioning “external access” in Docs) with 1:1 teams tenant irrespective of Teams upgrade mode settings in both party. “I was wrong”, only Teams native federation feature enabled the emojis, stickers, GIFs, and @mentions in your chat with rich chat experience between both party while both side users are in Teams Only mode.
Mostly large organisations are still in planning to go to completely in teams only mode and still their preferred mode is “Islands” mode. In Islnads mode, If you are having SFB onprem, then setup the federation with external users is messy and its recommended by Microsoft to have SFB online OR setup an error free SFB hybrid configuration to enable your onprem SFB users to initiate conversation with remote teams only mode user.
So, What is the workaround ?, untill you host your skype users to skype online or move users in teams only mode. Below are few ugly way, which you can use to enable your end-users to manage the conversation with external users (Customers, Partners and vendors).
Chat in meeting room conversation history
You can sent a Teams meeting invite to intended recipient and have a short conversation. Once conversation is over, you can see this meeting chat room saved in chat conversation history in left pane of Microsoft Teams window.
Now, when you need to IM to this external user, you can start your conversation from here and it would work.
Chat in Microsoft Teams Guest access
Another way to have chat with external users, is to use teams guest access feature. In Guest access, You also can invite any other users with a business or consumer email account, such as Microsoft 365, Outlook, Gmail, or others, can participate as a guest in Teams with full access to team chats, meetings, and files.
I shall not cover, How to enable the guest access in Teams in your tenant here. You can check Collaborate with guests in a team. You can also watch the below cool video to do it step by step.
Below are the feature available for users in Teams guest access. Ofcourse Teams admin do have full controls and can change the feature enable/disable as per the organisation and IT security need.
|Create a Channel (Teams Owner can control it)||Yes|
|Participate in a private chat||Yes|
|Participate in a channel conversation||Yes|
|Post, delete, and edit message||Yes|
|Share a channel file||Yes|
|Core call controls supported (hold, mute, video on/off, screen sharing)||Yes|
|Can add other user to a call via VOIP||Yes|
I hope above tips may help you to keep rolling your conversation with federated users.