Microsoft Teams allows users to chat one-on-one with members of the team, or chat with multiple members in a group or over a channel. Regardless of how you chat with someone, the people you can talk to are always limited to those in your organization.
Microsoft Teams has two different methods for allowing users to include outsiders in a team; guest access and external access. Both these modes have to be enabled from the Microsoft Teams admin center by a team admin or owner.
Microsoft Teams: Chat with external users
External users are defined as users who have an email address on a different domain than what Microsoft Teams is configured for.
For example, if your organization has emails configured on the domain myteamsdomain.com, then only users who have emails on this domain can be added to the team. All emails other than this one domain are considered ‘external’ domains and users who have emails on these external domains are external users.
Enable External Access in Microsoft Teams
In order to enable external access in Microsoft Teams, you need;
Access to the team admin account
The name of the domain you want to add a user from
We will be adding ‘gmail.com’ which allows us to add anyone who has a Gmail email as an external user to Microsoft Teams.
Visit the Microsoft Teams admin center.
In the column on the left, go to Org-wide settings>External Access.
Click ‘Add domain’.
Enter the domain you want to add.
Add external user
You’re now ready to add external users to Microsoft Teams. If you have the Microsoft Teams app open on your desktop, it’s a good idea to quit and relaunch it.
Open Microsoft Teams.
Go to the Chat tab.
Click the new conversation button.
Enter the email for the user you want to chat with.
Select ‘Search externally’.
Send the message.
Note: The user must sign up for Microsoft Teams. They can sign up for a free account but they must have a Microsoft Teams account in order to chat with you. Sending the message will send the user an invitation to chat with you.
Microsoft Teams: External user vs Guest user
An external user has far less access to your Microsoft Teams team than a guest user.
A guest user can;
View channels in a team
Send messages over channels
Communicate with other team members
An external user can;
Only chat with the Microsoft Teams team member that has added them
Can only participate in one-on-one chat with the user
Cannot join a meeting or view team channels
External access offers far fewer features compared to Guest access. An admin may enable it to allow team members to easily talk to people outside the organization. An admin may also choose to keep this particular feature off and if they so choose, you cannot work around it. You will not be able to talk to external users while signed in with your company’s Microsoft Teams account.