I think that Teams is one of the greatest tools Microsoft has ever released. I even think the way they went about developing the tool and not buying Slack was the right approach. I think how Slack gave them free publicity due to sour grapes was great for Microsoft Teams. And today we use Teams for just about all unstructured collaboration and integrate into SharePoint and other apps for structured collaboration. Recently Microsoft released the guest access for Teams and this has just changed the game. Now using your Office 365 or Azure AD login you can interact with people outside of your organisation in one location. There are so many applications for great productivity and genuine collaboration here, I’m sure your mind is exploding as has mine done just thinking about it. So without any further ado lets walk through enabling guess access for Microsoft Teams.
Connect to the O365 admin portal using a Global Admin account, and selected Settings > Services & Add-ins
Selected Microsoft Teams which opens the below view, selected Guest from the dropdown menu and Enabled the teams setting for Guests
Saved the changes.
And that's it.