How to enable 'external access' for collaborative work in Microsoft Teams?
How to enable 'External Access' in Microsoft Teams Admin Center
Browseto: https://admin.teams.microsoft.com/company-wide-settings/external-communications to enable external access.
Or follow the instructions in the video by going to: https://admin.teams.microsoft.com/ or https://admin.microsoft.com/
Users can communicate with other Skype for Business and Teams users.
Users can communicate with Skype users.
This may take up to 24 hours after activation.
Activate "Allow all external Domains" in the tab: Teams and Skype for Business users in external Organizations
How to enable guest access in Microsoft Teams Admin Center
To enable Remote Access for Microsoft Teams these settings are required.
External identities - Setting up external collaboration settings in Azure Active Directory (AD)
By default, each tenant set as shown below. Within this external identities panel, you can make adjustments to include less or more security.
Navigate to the Azure External Identities panel ->https://portal.azure.com/#blade/Microsoft_AAD_IAM/CompanyRelationshipsMenuBlade/Settings
Guest user access restrictions
This setting determines whether guests have full access to list all users and group memberships (most inclusive), restricted access to other users and memberships, or no access to other users and group memberships, including groups of which they are members (most restrictive).
Guest invite settings
Allow or block specific domains.
Block guest access to specific Microsoft Team sites
If you have enabled guest access but do not wish to welcome guests in some teams you can disable it in the SharePoint panel.
1. Use the SharePoint administrator panel
Browseto the SharePoint administrator panel from the admin centre. https://admin.microsoft.com
Select Sites, Active Sites
Select the desired team
Click on policy
2. Activate "Only people in the organisation".
Select between these 4 options: Only persons in the organisation
New and existing guests
Only existing guests
Only persons in the organisation
Other practical Microsoft Teams blogs
How to prevent users from deleting channels, tabs & apps in Teams
Communicating with external users in Microsoft Teams - meetings
How to share files in Microsoft Office 365 and Teams - 8 scenarios
How to import users and guests in CSV in Office 365 or Azure AD?
Adding multiple users to a Team at the same time