Collaboration is in Microsoft Teams' DNA; it's the very essence of what it was designed to do.
For most of us collaboration means working together on some bigger picture item, which could be a document, a report, a meeting pitch etc you get the idea, and this is where Microsoft Teams (and the rest of the Microsoft 365 stack) shines. It lets you share files, ideas, conversations and have meetings. For most scenarios, that works great, especially if everyone is part of the same organization. Working with people from different organizations can become trickier due to the legitimate issues surrounding maintaining data integrity and security.
In these scenarios, things such as sharing policies, identity management and data locations can cause some friction to that collaboration utopia we want. Microsoft Teams handles these in most scenarios by using the tenant as a natural boundary between users and having the notion of a guest account, where users can be invited into another tenant to share and work together. It's worth noting that alternative solutions, like Shared Channels, exist, but each option has its own advantages and disadvantages.
The challenge with guest access into another tenant is that the Microsoft Teams client only supports logging into one tenant at a time. You lose access to your home environment when you swap into another tenant to check for notifications or work on a document hosted there. You won't receive your incoming calls, chat messages or various alerts and notifications for the duration of your visit in that session. Yes, some workarounds can help, such as using different browser windows or tools such as Portals (https://github.com/jamescussen/PortalsReleases) and Firefox Containers, but this isn't a great experience overall and should be better.
Thankfully when Microsoft started re-architecting the new Microsoft Teams 2.1 client, this multi-account, multi-tenant issue was one that they sought to solve, and boy did they! Having used the new preview version of the client for a couple of months, I'm very pleased to report that the multiple account and cross-tenant support works flawlessly. Not just for the scenarios I outlined above where I need to work in multiple tenants, but even where I must work for different customers using completely alternative accounts.
The new Microsoft Teams client now has a drop-down menu in the top right-hand corner that lists all the accounts I have currently signed in, and the different tenants to which that account has guest access. The tenants have a little status indicator showing me quickly if the account is okay or shows a warning if I need to swap over and re-authenticate for any reason. But things get event better because now I also get an alert "roll-up" showing me where I have activity across any of these environments. I can click on the alert, and the client will swap me over to the right user/security context so I can see the alert and deal with it, but the real icing on the cake is that all the while I'm in these other accounts/tenants I am still logged in everywhere. To (badly) paraphrase the recent film, with Teams 2.1 I'm truly logged into Everything Everywhere All at Once.
No more missed incoming call notifications, no more incorrect presence statuses, no more being out of the loop, just living in the moment, in the correct context to do what I need. Have I mentioned yet that this all happens quickly? You can even swap between tenants on the fly while staying in an ongoing meeting or call. Try it; it's a little bit magical!
So, for now, yes, the 2.1 client is still in preview, it doesn't have all the features and bells and whistles of the primary client, but for me, it has become my daily driver as the true-multitenant experience trumps everything else and makes my day so much simpler.
Give it a go, and I'm sure you'll love it too if you've ever suffered from Teams tenant trauma…