Guest Access in Teams is different to external or federated contacts. Like you would invite a friend over for evening dinner, you are welcoming a guest into your company’s Teams workspace.
You can only invite a guest into a team that you have the privileges to. When invited, the guest receives an e-mail containing an invitation to join your team. When clicked they are able to access the team data and chat space as if they are an internal coworker.
The use case for this is primarily for temporary workers, perhaps external contractors who need to augment your team to help push a project over the line. As such they need easy access to project documents and chat to collaborate efficiently.
When they activate their guest join experience, they are seen as internal users and have a more enriched experience than when communicating over federation.
How to Grant a Guest Access In Teams
First, you need to have permission to do this. Most organisations restrict the permission due to the risk around data protection. If you are unable to add a guest, please contact your IT department.
However, assuming you have the necessary permission, you first need to choose the team you are inviting the guest to join. Once chosen, click on the ellipsis (…) next to the team title and choose Add Member

Enter the e-mail address of the guest you are inviting and when found click on Add

This will add them to the team and send them an e-mail

A View from the Guest Side
When invited, the guest will get an e-mail informing them and also when they expand the profile menu in their Teams client they will see your organisation


When they click on either of these, they must first accept the terms and conditions and permissions set out by your company or Microsoft

Once accepted, they will have access to the team you invited them to and all documents and chats within.

Communicating With Your Guest
Your guest will now be accessible using two identities. The first is their guest identity and the second, their external identity.

It is important to understand that they are two separate “people” in terms of how Teams treats them so chats and calls between you and them are not synchronised on their side.
Why is this important?
When a person is participating as a Guest they have to switch their Teams client into Guest mode and login as that guest account. This means that if you send a chat message or try to call their external account, they are not going to receive that until they switch back to that identity and vice versa.
Remove a Guest
To remove a guest from your team, click on the ellipsis (…) next to the team title and select Manage Team

Find the Guest to remove and click the X Icon

In removing the guest they will still have access to their guest account and be able to chat to people directly within your company. To remove them fully is a task for your IT Administrator.