despite configuring as per the MS documentation, b2b direct connect will not let me add an external user to a Teams shared channel. How can I debug it?

Hi @petehall

According to the official documentation of Teams, Teams enables external sharing of shared channels by default, and you must also configure the Microsoft Entra cross-tenant access settings for B2B Direct Connect to share channels externally. By default, these settings are set to block all organizations.

You can change the B2B Direct Connect default settings to allow all organizations. Please note that the organization you are working with must also configure its B2B Direct Connect settings. Based on the settings you provided, this is most likely the cause of the problem.

If your problem cannot be solved, please follow the steps to reconfigure the collaboration permissions with external participants:

• Microsoft Entra External ID External Collaboration Settings: Sharing in Microsoft 365 is managed at its highest level by the B2B external collaboration settings in Microsoft Entra External ID. Check the external collaboration settings to ensure that sharing with guests is not blocked.
• Teams guest access settings: The "Allow guest access in Teams" setting must be "On" for guest access to work in Teams.
• Microsoft 365 Groups guest settings: Teams uses Microsoft 365 Groups for team membership. The Microsoft 365 Groups guest settings must be turned on in order for guest access in Teams to work.
• SharePoint organization level sharing settings: Teams content such as files, folders, and lists are all stored in SharePoint. In order for guests to have access to these items in Teams, the SharePoint organization-level sharing settings must allow for sharing with guests.
• SharePoint organization-level default link settings: The default file and folder link settings determine the link option that's shown to users by default when they share a file or folder. Users can change the link type to one of the other options before sharing, if desired.
• Enable shared channels in Teams.
• Enable external access: In the Teams admin center, expand Users, and then select External access. Under Teams and Skype for Business users in external organizations, ensure that the organizations that you want to collaborate with are not blocked.
• Specify a link to your internal process for requesting new external organizations: For users to invite people from outside your organization to a shared channel, both organizations must set up an organizational relationship in Microsoft Entra B2B direct connect.
• Configure cross-tenant access settings in Microsoft Entra External ID: Microsoft Entra External ID B2B direct connect is disabled by default. To enable collaboration in shared channels with people from other organizations, you must:
  1. Add an organization.
  2. Configure inbound settings for the organization to allow users from the organization to be invited to your shared channels.
  3. Configure outbound settings for the organization to allow your users to be invited to the other organization's shared channels.

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