---
title: "About the upgrade"
canonical: "https://help.callroute.com/space/CKB/2633760769/About%20the%20upgrade"
format: markdown
---
If your organisation currently uses the legacy Voice4Teams service, your existing users will be migrated to the new **Callroute-powered Voice4Teams service**.

The migration is designed to be **zero touch** after you complete the Microsoft 365 authorisation from the **8x8 Admin Console**. You do not need to access Callroute, select users or manually start the migration.

## How the upgrade works

### 1. Authorise Microsoft 365

The upgrade process starts when you complete the Microsoft 365 authorisation from the **8x8 Admin Console**.

This establishes the connection between Callroute and your Microsoft 365 tenant and provides the permissions required to configure Voice4Teams.

### 2. Your existing Voice4Teams users are identified

Once authorisation is complete, Callroute automatically synchronises the required Microsoft 365 information and identifies your existing legacy Voice4Teams users.

Callroute compares the Voice4Teams information supplied by 8x8 with Microsoft 365 to ensure that the users and telephone numbers required for migration can be correctly identified.

No customer action is required during this stage.

### 3. Upgrade starts automatically

Once the identification checks have completed successfully, the upgrade starts automatically.

Immediately before the upgrade, Callroute refreshes the identification information to ensure the latest available user information is used.

The upgrade is performed as a **whole-tenant cutover**. All existing legacy Voice4Teams users within the tenant are upgraded together. Partial upgrades is not supported.

### 4. Users are moved to Callroute Voice4Teams

During the upgrade, Callroute applies the Microsoft Teams configuration required for the new Voice4Teams service and enables the Callroute connection to the users' 8x8 service.

Your **8x8 PBX remains the underlying telephony platform**. The upgrade changes the service used to connect your 8x8 users to Microsoft Teams.

### 5. Legacy registration is disabled

Once the upgrade has completed, registration through the legacy Voice4Teams service is disabled.

This ensures that users register through the new Callroute-powered Voice4Teams service and prevents calls from being presented through both the legacy and new services.

The legacy configuration is retained during the migration period so that it can be restored if a rollback is required.

### Important – Action following your migration

Following migration, some users may experience issues receiving inbound calls while Microsoft Teams updates its calling configuration.

> ⚠️ **All Microsoft Teams users – Sign out and back in**
> ⚠️ 
> ⚠️ To avoid potential calling issues, we strongly recommend that ALL users sign out of Microsoft Teams on **ALL** devices (including desktop and mobile) and then sign back in.
> ⚠️ 
> ⚠️ <span style="color: #ff5630">**Administrators: Please ensure this instruction is communicated to all Microsoft Teams users following the migration**</span>

## What do I need to do?

Once you have successfully completed the Microsoft 365 authorisation, **no further action is normally required**.

The identification and migration stages are performed automatically.

For the initial rollout of the new Voice4Teams service, access to the Callroute portal is provided **after the migration has completed**.

## What happens if there is a problem?

If Callroute cannot successfully identify or validate the users required for the upgrade, the upgrade will not proceed until the issue has been resolved.

If a problem is identified after migration, the retained legacy configuration allows the service to be rolled back if required, including restoring legacy registration.

See **[Troubleshoot user identification](https://callroute.atlassian.net/wiki/spaces/CKB/pages/2632122381)**[ ](https://callroute.atlassian.net/wiki/spaces/CKB/pages/2632122381)for identification issues and **[Understand registration during the upgrade ](https://callroute.atlassian.net/wiki/spaces/CKB/pages/2632089631)**for more information about how registration changes during the cutover.