How to Transfer Microsoft Teams Phone Numbers Between Tenants
Question details
The user needs to move Microsoft Teams phone numbers from one Microsoft 365 tenant to another, which involves reassignment and voice-routing changes.
- Product
- Microsoft Teams
- Device & OS
- not provided
- Scenario
- Migrating a telecommunications infrastructure during a tenant-to-tenant migration.
- Observed behavior
- The goal is to safely transfer voice routing and phone numbers across Microsoft 365 tenants without causing FQDN conflicts.
Ensure you have global administrator or Teams administrator privileges in both the source and destination Microsoft 365 tenants before initiating the transfer.
Transfer Microsoft-Provided Phone Numbers via Support Request
This is the recommended method to migrate native Microsoft Teams calling plan numbers between two Microsoft 365 tenants.
Because Microsoft manages the underlying carrier for these numbers, they must manually intervene to move the block of numbers from the source tenant ID to the destination tenant ID.
Log into the Microsoft Teams admin center in the source tenant. Navigate to Voice > Phone numbers, select the numbers you wish to migrate, and unassign them from the current users or resource accounts.
Open the Microsoft 365 admin center, go to Help & support, and submit a service request. Ask Microsoft to transfer the specific unassigned phone numbers from your source tenant to the destination tenant, providing both Tenant IDs.
Once Microsoft confirms the transfer is complete, log into the destination tenant's Teams admin center. Locate the newly transferred numbers under Voice > Phone numbers and assign them to the corresponding users.
Reconfigure Direct Routing and SBC FQDN
If you use Direct Routing to connect a third-party carrier, you must update your Session Border Controller (SBC) configuration.
Manage Your Migration Plans Efficiently with WPS Office
While migrating Microsoft Teams configurations requires Microsoft admin portals, WPS Office provides a lightweight, highly compatible alternative for drafting migration plans, documenting voice routes, and managing user communication spreadsheets.
Frequently Asked Questions
How long does it take for Microsoft to transfer Teams phone numbers?
The timeframe can vary depending on Microsoft support queues and the complexity of the request. It typically takes a few business days, so plan for appropriate maintenance windows and coordinate closely with Microsoft support.
Can I share a Direct Routing SBC between two tenants during migration?
Yes, but you cannot use the exact same base FQDN in both tenants simultaneously. You typically need to configure a wildcard certificate and use derived FQDNs (e.g., tenant1.sbc.domain.com and tenant2.sbc.domain.com) for multi-tenant SBC setups.
Will users lose their voicemail data during the phone number transfer?
Voicemail messages reside in the user's Exchange Online mailbox. As long as the user's mailbox is successfully migrated to the new tenant alongside the Teams migration, old voicemails should be retained, though new routing rules will need to be applied.
