This Ideas is related to the following Microsoft Ideas:

https://experience.dynamics.com/ideas/idea/?ideaid=20dee30e-8d9c-ed11-9ac4-0003ff45ac2b

*Assumptions: User from tenant B is a guest user in tenant A and access the BC environment in tenant A.

In case of teams integration

When a guest user opens any table record from the Sales Hub app and initiates a Teams chat, the contact can only see users from his/her tenant.

We have confirmed in the MS doc below that this is by design.

https://learn.microsoft.com/en-us/microsoftteams/trusted-organizations-external-meetings-chat?tabs=organization-settings#manage-chat-with-external-teams-users-not-managed-by-an-organization

However, this is very inconvenient for the end user.

If this feature is implemented, it will make Teams integration more convenient.