External access and guest access in Microsoft Teams
The four ways outsiders can collaborate with you in Teams — and the trade-offs between guest, external access, shared channels, and anonymous join.
Outside collaboration in Microsoft Teams is a confusingly named topic because the terms overlap. There are actually four distinct mechanisms, and choosing the right one matters for both security and user experience.
1. Guest access
A guest is someone you add as a full member of one of your teams using their existing email address. They get a guest identity in your Entra ID directory and can chat in channels, access files, and join meetings — almost like a regular member, but with restricted permissions and visibility into your tenant.
Use guest access for deep, long-term collaboration with someone outside your organisation (a consultant embedded in a project for a year, for example).
2. External access (federation)
External access is one-to-one chat and calling with people in other Microsoft 365 tenants — and, optionally, with Skype consumer users. It's federation between tenants. The other party stays in their own tenant entirely; you just exchange messages and calls. No file sharing, no team membership.
Use external access for direct messaging with counterparts at other companies.
3. Shared channels (Teams Connect)
A shared channel lets you invite people from other Microsoft 365 tenants into a specific channel, without making them members of the team or guests in your tenant. They keep their home identity; your tenant publishes the channel via Entra ID Cross-Tenant Access Settings.
Use shared channels for ongoing cross-organisation collaboration that doesn't justify guest accounts. This is the most modern option and the one Microsoft is investing in.
4. Anonymous join
In a meeting, you can let people join anonymously without any identity at all — they enter a name and join the lobby. Useful for one-off meetings with people who don't have Teams.
How to choose
| Need | Mechanism | | --- | --- | | Long-term embedded contractor | Guest | | Direct chat/call with another tenant | External access | | Ongoing cross-tenant project channel | Shared channel | | One-off external meeting attendee | Anonymous join |
Admin controls
All four are toggled separately. In the Teams admin center, External access controls federation; Guest access toggles allow guests at all. Shared channels are governed by Cross-Tenant Access Settings in the Entra admin center. Anonymous join is a meeting policy. A common mistake is to ask "is Teams open to outside people?" without distinguishing which of these four is meant.