01 Foundations

• Confirm the tenant, the verified domain, and the admin role before you touch a voice route.

• A resource account is disabled for interactive sign-in. It still needs the license the voice app requires.

• Calling Plan, Operator Connect, Teams Phone Mobile, and Direct Routing can live in one tenant. They are not the same purchase.

• Treating a guest, or an admin in the wrong tenant, as if they can grant a voice routing policy.

• Opening an SBC ticket when the domain is unverified and the user has no Teams Phone license.

Facts in the long lessons were checked 14 October 2026. This sheet is a memory aid.

Sources and go deeper

Plan Direct Routing — Microsoft Learn — last checked 2026-10.
Use Teams admin roles — Microsoft Learn — last checked 2026-10.
Microsoft 365 — Wikipedia — last checked 2026-10. Wikipedia fallback for background. Confirm the vendor page before you change a tenant
Microsoft Teams — Wikipedia — last checked 2026-10. Wikipedia fallback for background. Confirm the vendor page before you change a tenant
Microsoft Teams blog index — Community — last checked 2026-10. Community index for the Microsoft Teams blog. This is the index, not a claim that a post discusses this room
Manage resource accounts — Microsoft Learn — last checked 2026-10.
Security, Compliance, and Identity Fundamentals — Microsoft Learn — last checked 2026-10.
Set up Teams Phone — Microsoft Learn — last checked 2026-10.
Cloud Voicemail — confirm — last checked 2026-10. Did not open when checked. HTTP 404.
Set up Cloud Voicemail - Microsoft Teams | Microsoft Learn — Microsoft Learn — last checked 2026-10. Opened in place of a page that did not open when checked. The title is the page that opened