B2B Address Book Sharing

Currently, Microsoft Teams does not offer a built-in B2B Address Book that automatically suggests external contacts from organizations with which you have a Cross-Tenant Access Policy configured. However, here are some workarounds:

1. Using Azure AD B2B Collaboration (Guest Accounts)
If external users are added as guests in your tenant (via Azure AD B2B collaboration), their names will be available in Teams when typing. However, this method requires manual invitation and approval.

2. Enabling Shared Channel (Teams Connect)
If you use Teams Shared Channels, external users from the other organization will appear in your Teams directory when you type their names. This feature works without requiring them to be added as guests.

3. Custom Solution via Power Automate / PowerShell
For a more automated approach, you could:

• Sync frequently contacted external users into a custom Contacts List (SharePoint, Dataverse, or Outlook).
• Use Power Automate to update a shared Teams contact list.
• Query Microsoft Graph API to retrieve external contacts and enable easier searching.

4. Outlook Contact Sync
If the external users are frequently emailed, you can:

• Add them as contacts in Outlook (this syncs with Teams search).
• Use Exchange Address Book Policies to create a shared contact list.