Microsoft created a wonderful communication app with Teams (imho) but specially in the area on who is who and who can do what there can be a lot of confusion due to the complexity of options and considerations.

With this post I will give a summary to the concept of Team members vs Team Guests vs External users with focus on direct communication and the most important differences. Full overviews are linked in the text and in the links section at the bottom of the post.

A full Teams user

A full Teams user is someone who is part of a licensed Office365 setup or a free Teams account and can:

• Chat or Call (1:1 or Group) to any other user that is part of the same organisation;
• Chat or Call 1:1 to any External user, either with full capabilities (both you and the user are on Teams Only mode) or with restricted capabilities (one of you is not on Teams Only mode);
• Chat or Call (1:1 or Group) with Team Groups Guests registered within your organisation (users from outside your organisation who are added to any Team Group);
• Setup Meetings and invite other users from the same organisation, External Users and Team Group Guests (Note: Meetings creation is excluded from the free Teams plan);
• be a Team Group Member and have Channel Conversations and Meetings with the other Team Group Members and Team Group Guests;
• be a Team Group owner and act as Team Member with extra Group management rights;

An External user

External users are people from outside your organisation from a licensed domain using Skype for Business or Teams and who you contact from within Teams by adding their e-mail address for a 1:1 Chat or Meeting and selecting the option “… search externally” when presented.

External users are marked with a “External”-label behind their e-mail address. This works also the other way around where you will also be marked as External at your external contacts Chat and Contact lists.

IMPORTANT:

1. External users receive Chats and Activity Notifications in their own organisations Teams panel. (No switch organisation opposite to being a Guest) !!!
2. You can contact Guest users on their Guest user labelled e-mail address NEXT TO this same user External labelled contact address in case this also exist among your contacts list;
3. Communication features between External contacts are restricted compared to users within your organisation or Guests.
4. External access has to be allowed and configured for your and your contacts domain.
5. Native Chat experience only between external users that are both on Teams Only mode!
6. External users can share and get a desktop shared but can not get control from a shared desktop from another user.

A Guest

Guests are users from other organisations that are added as members to one or more Team Groups (aka Team Group Guest Members).

The same way you can be a guest in Team Groups belonging to other organisations then your own.

Guest members are basically visiting, in digital person so to say, your online organisation like they would in the physical world by visiting your office and can collaborate as such within your Team Groups they are member of. Therefor Guests need to switch to your organisation within the Teams app and can (with some restrictions, see point 4 below):

• collaborate in Team Group Channels;
• contact other users in your organisation via chats and calls;
• attend meetings
• NOT create meetings from within the org they are guest of. (Calendar feature is part of your orgs Office and can not be accessed (yet) from within an other org view)

IMPORTANT:

1. Guest users receive Chats and Activity Notifications in the OTHER organisations Teams panel. SWITCH organisation is needed within Teams to work as Guest !!!
2. You can contact External users on their external user labelled e-mail address NEXT TO this same user Guest labelled contact address in case this also exist when this user is also any Team Group Guest;
3. Guest members have some restrictions compared to full Team members;
4. Some settings for Guest users can be managed per Team by Team owners and some org-wide settings can be managed by org-admins;
5. As a Guest user you can leave an organization on your own free will (account need to be enabled on both the home and the guest tenant) but an organizations admin has to fully remove your profile from the specific guest tenant.

Further reading on the full explanation and info provided by Microsoft:

For All Team Users

• Communicate with users from other organizations in Microsoft Teams
• Native chat experience for external (federated) users in Microsoft Teams
• Compare external and guest access
• What the guest experience is like
• Comparison of team member and guest capabilities
• Team owner, member, and guest capabilities in Teams
• Set guest permissions for channels in Teams
• Leave an organization as a guest user

For Admins

• Manage external access in Microsoft Teams
• Authorize guest access in Microsoft Teams
• Teams and Skype interoperability
• Manage Guest access in Teams
• Turn on or turn off guest access to Microsoft Teams
• Guest access checklist
• Remove fully a guest user from an organization

I hope this post made your journey on communicating and possible home work with #MicrosoftTeams during this time of Corona easier and more productive.

Feel free to contact me or leave any comment if you have remarks or suggestions.

Stay safe and see you online!

Martinus