Guests cannot join a Teams shared channel — only people from another Microsoft 365 organisation can
A shared channel is the natural answer to "the architect should see one channel, not the whole team" — but it only works for people whose company has its own Microsoft Entra tenant, and only after both organisations allow each other in cross-tenant access settings (B2B direct connect). A guest account (B2B collaboration) cannot be added to a shared channel at all. Before you promise "external partners get their own shared channel", ask whether each partner has Microsoft 365; for those who don't, plan guest access to the library or a separate site instead.
Sdílený kanál je přirozená odpověď na „architekt má vidět jeden kanál, ne celý tým“ – funguje ale jen pro lidi, jejichž firma má vlastní tenant Microsoft Entra, a jen když si obě organizace povolí propojení v nastavení přístupu mezi tenanty (B2B direct connect). Účet hosta (B2B collaboration) do sdíleného kanálu přidat nejde vůbec. Než slíbíte „každý partner dostane sdílený kanál“, zjistěte, kdo z partnerů má Microsoft 365; pro ostatní naplánujte přístup hosta do knihovny nebo na samostatný web.
Symptom
A collaboration design — a proposal, a prototype, a team template — puts external partners (an architect, a contractor, a supervisor) into a shared channel of the project team so they see their channel and nothing else. When it is built:
- the owner tries to add the partner to the shared channel and the partner is not found in the people picker — B2B direct connect is blocked by default until both organisations allow it;
- a partner who was invited to the team as a guest sees the team's standard channels, but the shared channel never appears for them;
- partners from a company with Microsoft 365 work fine, partners using a personal or non-Microsoft address do not.
Cause
Teams has two different external-access mechanisms and they do not mix:
| Guest access (B2B collaboration) | Shared channel (B2B direct connect) | |
|---|---|---|
| Who | anyone with an e-mail address | users of another Microsoft Entra organisation |
| Account in your tenant | yes, a guest user | no |
| Setup | guest access enabled | cross-tenant access settings configured by both organisations, plus guest access in Teams enabled |
| Scope | the whole team (standard channels, files) | only the shared channel |
Microsoft states it directly: guests "can't be added to a shared channel"; external people participate through B2B direct connect, which requires a mutual trust relationship between the two tenants. A guest invited to the team also cannot see or participate in the team's shared channels.
Fix
Design for both kinds of partner up front:
- Partner with their own Microsoft 365: shared channel via B2B direct connect. Agree the cross-tenant access settings with the partner's IT once (inbound on your side, outbound on theirs; trust their MFA if your conditional access requires it).
- Partner without Microsoft 365: invite as a guest, but not to the whole team if they should see only part of it. Give access to the specific library folders or a separate partner site, with an expiry date on the guest's access.
- In proposals and templates, say which of the two you mean — "shared channel" quietly assumes the partner has Microsoft 365.
Sources
- Shared channels in Microsoft Teams — "guests … can't be added to a shared channel"; cross-tenant access settings required by each organisation.
- B2B direct connect overview — mutual trust between two Entra organisations; guest users can't see or participate in shared channels.