A recurrent question from my Customers is "Could it be possible to make calls between Remote Assist Users belonging to different M365 Tenants?"
The short answer would be no, but let's go into depth to find out why.
Looking at the cross-tenant communication official documentation, we can find procedures on how to configure our Tenants and our users in order to permit a dual communication between them using MS Teams and configuring those users as a Guest User from one Tenant in the other one.
In this scenario, it will be possible for a MS Teams User to establish a communication with a Guest User from another Tenant using MS Teams, as long as the Guest User will be logged into his MS Teams App (both Web and Desktop) and joined to the Azure Directory in which his account is configured as a Guest.
Just extending this scenario, it could also be possible for a Remote Assist user in a tenant, using either the HoloLens App or Mobile Device App, establishing a communication with a Guest user using MS Teams, as long as that MS Teams user will be correctly logged in into the App and joined to the right Azure Directory.
Based on previous requirement for a Guest user using MS Teams to be joined to the right Azure Directory, it is clear why the communication between two Remote Assist users on devices from different Tenants cannot be established: because it is not possible to switch the Azure Directory! In fact, into all the kind the Remote Assist App, the Azure Directory is the one associated to the Tenant owing the User without any possibility to change it.
I hope this helps to clarify with your customers too!
With regards,
Marco Brizi
