The Problem:

Microsoft Teams users may encounter communication issues when attempting to connect with external domains or trial tenants. These issues can manifest as an inability to send or receive messages, join meetings, or access shared resources with users outside the primary organisation's domain.

Problem Analysis:

Symptoms of this issue include failed message delivery, error notifications when attempting to join external meetings, and lack of access to shared files or resources with external domains. These issues often begin when organisations attempt to collaborate with partners or clients using trial tenants or domains that have not been properly configured for external access.

Root Cause:

The root cause of these communication issues is typically related to the configuration settings of the tenant federation in Microsoft Teams. By default, certain settings may restrict communication with external domains and trial tenants. Specifically, the ExternalAccessWithTrialTenants setting may not be set to allow communication, thereby blocking interactions with these external entities.

Solution:

To resolve communication issues with external domains and trial tenants in Microsoft Teams, follow these steps to adjust the tenant federation configuration:

1. Open PowerShell with Administrative Privileges:

Ensure you have the necessary administrative rights to execute PowerShell commands.

2. Install the Teams PowerShell Module (if not already installed):

   Install-Module -Name PowerShellGet -Force -AllowClobber

   Install-Module -Name MicrosoftTeams -Force -AllowClobber

3. Connect to Microsoft Teams:

Use the following command to connect to your Microsoft Teams environment:

   Connect-MicrosoftTeams

4. Check Current Tenant Federation Configuration:

Retrieve the current configuration to understand the existing settings:

   Get-CsTenantFederationConfiguration | FL

Review the output to check the status of ExternalAccessWithTrialTenants.

5. Allow External Access with Trial Tenants:

If the ExternalAccessWithTrialTenants setting is not set to "Allowed", update the configuration:

   Set-CsTenantFederationConfiguration -ExternalAccessWithTrialTenants "Allowed"

This command modifies the configuration to permit communication with trial tenants.

6. Verify the Changes:

After making the changes, verify that the configuration has been updated:

   Get-CsTenantFederationConfiguration | FL

Ensure that ExternalAccessWithTrialTenants is now set to "Allowed".

7. Test Communication:

Attempt to communicate with the external domain or trial tenant to confirm that the issue has been resolved.

By following these steps, you should be able to resolve communication issues with external domains and trial tenants in Microsoft Teams, enabling seamless collaboration.