M365 Cross-Cloud and Cross-Tenant Collaboration Scenarios
Published Nov 16 2021 09:41 AM 35.1K Views

As more of our customers onboard onto our government clouds (GCC, GCC High and DoD) they also need to be able to collaborate across those boundaries. Many cross-cloud scenarios are enabled and available today, with more coming in the future. The aim of this post is to document them and continually update it with the latest capabilities as they come online. To make it easier to consume, my colleague @Paul Meacham and I created a series of videos illustrating how each one works and what steps you need to take to configure them, when necessary. Here’s the current list:


Cross-Cloud Teams Chat and Teams Voice Calls (1:1)


This video shows how you can quickly start a 1:1 chat with a user from a different cloud.


Pre-requisites: Currently, the prerequisite is to explicitly add the cross-cloud domain to your list of externally allowed domains, following the instructions on this article:

Manage external access (federation) - Microsoft Teams | Microsoft Docs





Cross-Cloud File Sharing using one-time passcode (OTP) from SharePoint Online or OneDrive for Business


Here we show how easy it is to share a file (or multiple files) with a user from a different cloud so that they can even coauthor on that file if you give them Edit permissions


Pre-requisites: External sharing needs to be enabled for SharePoint Online (SPO) and OneDrive for Business (ODfB), the following articles provide great guidance around enabling secure external sharing:


Collaborating with people outside your organization | Microsoft Docs

Create a secure guest sharing environment | Microsoft Docs

Microsoft 365 guest sharing settings reference | Microsoft Docs




Cross-Cloud Calendar Free-Busy Sharing and Anonymous Meeting Join



To collaborate across clouds via meetings, sharing Free/Busy information is vital and that’s one of the features we highlight on this video as a precursor to the cross-cloud meeting experience. Then we show how Anonymous Meeting Join allows users from other clouds to join cross-cloud meetings.


Some details that are worth mentioning here: when joining a O365 GCC High meeting from O365 Commercial, the user will get a specific message stating that they must copy and paste the meeting URL into a browser window and continue to use the browser experience. For other scenarios, such as joining a DoD meeting from GCC High, or joining from DoD to Commercial users don’t get this prompt so it’s important to remind users to join all cross-cloud meetings from the browser. Teams engineering is working on enabling a seamless anonymous meeting join experience (to and from all clouds) by early calendar year 2022.


Pre-requisites: Enable Anonymous meeting join

Manage meeting settings - Microsoft Teams | Microsoft Docs

Setup Cross-Cloud Free Busy sharing

Create an organization relationship in Exchange Online | Microsoft Docs




Cross-Tenant Teams Guest Access (GCCH)



This video shows the most requested feature in GCCH which is now Generally Available (GA): Teams Guest Access. Organizations can now invite users from other tenants into Teams they own to enable rich collaboration, coauthoring, channel meetings, and file sharing, to include meeting recordings.


Pre-requisites: Guest Access and Sharing with Guests needs to be enabled on the tenant

Collaborate with guests in a team | Microsoft Docs

Create a secure guest sharing environment | Microsoft Docs




Please try these scenarios out and provide your feedback in the comments section. Paul and I will be checking the comments and making updates to this post as soon as we release new capabilities or make improvements to the existing ones.

Copper Contributor

Are any of these available as of today (GA, preview, etc)? 


@tonyladha yes they are all available today. 


Great job @Sergio Cossio  thank you for the write up


Hey Sergio! Are there updates to these capabilities from the last couple of months? 

Copper Contributor

@Sergio Cossio - I'm specifically looking for the Azure B2B Commercial to GCCH guest user functionality.  We have both Commercial and GCCH tenant and really hoping we can add guest users cross clouds for basic user auth.  We don't even need Teams access.

Brass Contributor

Now that Teams shared channels are out, what is the experience with shared channels in a cross-cloud environment? 

Copper Contributor

Paul and Sergio,


Thank you for this documentation.  A few of my customers have been looking forward to seamlessly collaborate between GCCH and Commercial tenants with O365 online apps.  One customer approached us to discuss options which are not well documented.  Their organization is currently in a GCCH tenant with M365 GCCH organization.  They frequently must collaborate with partners, vendors, etc. in Commercial tenants and M365 orgs.  They have been considering deploying both GCCH and Commercial tenants and M365 orgs due to issues collaborating from GCCH and Commercial tenants mainly with O365 Online apps.  That opens a whole can of worms since they are discussing options to sync identities from AD DS to GCCH and Commercial tenants and want SSO.  I do not believe that is possible w/o a lot of pain, caveats, and limitations.  One issue they mentioned is even with these new features, they feel the Teams web client does not offer the same features as the Teams desktop client.  I see that support for the Teams desktop client is still in development in several of the diagrams.  Also that Azure B2B between GCCH and Commercial tenants is still in development.  Is there any roadmap that can be shared?  I am a MISA member, a member of an organization that is a Microsoft Gold Partner, and we just went through several product roadmaps under NDAs.  Unfortunately these roadmaps do not mention cross-tenant collaboration between GCCH and Commercial tenants.  I must admit I stumbled upon this blog and sometimes find it hard to know how to search for Microsoft information and who to contact for information.   



Gary Howard

Copper Contributor

Hi @Sergio Cossio  and Paul Meacham,

What is the latest status of Teams Meetings including some users from GCC High tenant and other users from a trusted Commercial Cloud tenant? The third scenario demonstrated here shows these meetings are possible if the user joining the meeting (1) uses the browser not the Teams client and (2) joins the meeting as an anonymous user. Please correct me if I'm mistaken, but security would be compromised by enabling anonymous join; anyone who obtains the link could join the meeting and spoof their name. With that security problem my client cannot use Teams meetings between their GCC High tenant and their partner's Commercial cloud tenant. Please provide best compromise recommended.


Martin Cox

Copper Contributor

Any update on when Teams engineering will release the following feature?


"Enabling a seamless anonymous meeting join experience (to and from all clouds) by early calendar year 2022."

Copper Contributor

Hi @Sergio Cossio and @Paul Meacham, this is a great blog but outdated given the pace of changes in the GCC High environment. Can you reference an any updated documentation or links? Thanks!

Copper Contributor

Will this allow cross-agency information sharing?  For example, can I share an SP list from VA to DHS or HHS partners (no PII or PHI, of course)?

Brass Contributor

I'd really like to know this too @Sergio Cossio and @Paul Meacham,

Copper Contributor

Is there any update to this?  About 4 months ago, I posted asking if I could share an SP list between federal agencies; no answer.  I'd also like to know if I can share PowerBI reports and dashboards.


HeatherGLong yes, the technology/features are now fully available to enable sharing between tenants across cloud boundaries, however that is still subject to the governance policies of the source and destination tenants. This mean that yes you can configure say a GCCH tenant to accept Guests from GCC or DoD, BUT the tenant owners may not want to enable that, so the policy/governance work needs to be championed by folks like you who desire to take advantage of these capabilities. 

Re: PowerBI, here's some info: Distribute content to external guest users with Microsoft Entra B2B - Power BI | Microsoft Learn

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