Enterprise Teams user shown as offline, but actually online. Not receiving Chats.

[Joseph Nierenberg]

I was meeting today over Teams with someone from another company. They use Teams extensively. I tried to send her a chat during our conversation by using the Chat tab and opening a new Chat with her, instead of using chat in the meeting (because the purpose was to see whether I could @mention her in chat and she'd receive a notification.) My Teams said she was offline and an e-mail would be sent to her. The presence indicator in my Teams also showed her as offline. My Teams also showed a Skype symbol near her name and noted that she was External. But she was clearly online--we were using Teams and she was in her own userspace. Why was she shown as offline, and what can her IT folks do to make it more functional?

[#2 · Accepted solution]

The external IT can check if a federation between two Microsoft Teams org are allowed or not:
https://docs.microsoft.com/en-us/microsoftteams/manage-external-access?WT.mc_id=M365-MVP-5004286#all...
Also they can check the Teams Upgrade settings, perhaps the Teams co-existence mode Island is still enabled.

[#3]

@Joseph Nierenberg 

My guess will be the same as @Thorsten Pickhan, It probably has something to do with the Teams Upgrade mode in the tenant of the external user. The behavior you see (like chat not received and seeing an SfB symbol) fits into the “island mode”. 

[#4]

@Mitchell Bakker @Thorsten Pickhan  Thank you both. I forwarded this on to two clients with whom I have the issue. I haven't heard back yet, but it seems likely that you've identified the problem.