What's the difference between external access and guest access in Teams?
This confuses almost everyone. Both let outsiders join your tenant, but in completely different ways. External access is federation: your tenant talks to their tenant. Guest access is inviting someone into your tenant. Which one you pick depends on what the external party needs to do.
Try this first
- 1External access (formerly federation) is for chatting or calling across tenants, like another department. The external person stays in their own tenant, doesn't log into yours. Works for one-to-one chat, audio/video calls, seeing presence. No access to channels or files.
- 2Guest access is for when the external person needs to participate in a team: read channels, edit files, join scheduled Teams meetings. The guest gets a guest account in your tenant (B2B in Entra) and logs into yours.
- 3Configure external access in Teams admin > Users > External access. You can allow- or blocklist domains. For B2B work you usually enable it for specific partner domains.
- 4Configure guest access in Teams admin > Users > Guest access on, and in Entra ID > External Identities > External collaboration settings. Both must align, otherwise 'Add guest' doesn't show or invites don't arrive.
- 5Test both flows with a test account in another tenant (or a colleague with a personal account for guest). Document which partner domains are open, otherwise you lose track.
When to bring us in
If you work with many external parties (build teams, consultants, vendors) and it gets unmanageable who has access where, an hour of access review pays off. Removing inactive guests cuts risk and cost.
See also
- Outlook crashes or freezes on large attachmentsUsually the mailbox cache is the culprit, not Outlook itself. Shrinking or relocating usually helps within ten minutes.
- Teams: they cannot hear me, or I hear nothingIn our experience Teams usually picked the wrong audio device after a Windows update or a new headset.
- OneDrive has stopped syncingThe cloud icon is grey or has a warning. Locally changed files are not showing up for colleagues.
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