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Using the Meeting Migration Service (MMS)

The Meeting Migration Service (MMS) is a service that updates a user’s existing meetings in the following scenarios when:

  • A user is migrated from on-premises to the cloud.
  • An admin makes a change to the user’s audio conferencing settings.
  • An online user is upgraded to Teams only, or when a user's mode in TeamsUpgradePolicy is set to SfBwithTeamsCollabAndMeetings.
  • A Cloud Video Interop (CVI) partner is migrating to another. In this scenario the tenant key will be updated to reflect the new partner.
  • Admins use Start-CsExMeetingMigration cmdlet within the Teams PowerShell module.

By default, MMS is automatically triggered in each of these cases, except in the case of CVI migration. For CVI, MMS will need to be executed manually once the CsTeamsVideoInteropServicePolicy is changed to reflect the new partner. In addition, admins can use a PowerShell cmdlet to manually trigger meeting migration for a given user.

Limitations: The meeting migration service can't be used if any of the following apply:

  • The user’s mailbox is hosted in Exchange on-premises.
  • The user is being migrated from the cloud to Skype for Business Server on-premises.

How MMS works

When MMS is triggered for a given user, a migration request for that user is placed in a queue. To avoid any race conditions, the queued request is deliberately not processed until at least 90 minutes have gone by. Once MMS processes the request, it performs the following tasks:

  1. It searches that user’s mailbox for all existing meetings organized by that user and scheduled in the future.
  2. Based on the information found in the user’s mailbox, it either updates or schedules new meetings in Teams for that user, depending on the exact scenario.
  3. In the email message, it replaces the online meeting block in the meeting details.
  4. It sends the updated version of that meeting to all meeting recipients on behalf of the meeting organizer. Meeting invitees will receive a meeting update with updated meeting coordinates in their email.

Screenshot that shows the meeting block that gets updated by MMS.

From the time MMS is triggered, it typically takes about 2 hours until the user’s meetings are migrated. However, if the user has a large number of meetings, it might take longer. If MMS encounters an error migrating one or more meetings for the user, it will periodically retry up to 9 times over the span of 24 hours.


  • MMS replaces everything in the online meeting information block when a meeting is migrated. Therefore, if a user has edited that block, their changes will be overwritten. Any content they have in the meeting details outside of the online meeting information block won't be affected. This means any files attached to the meeting invite will still be included.
  • Only the Skype for Business or Microsoft Teams meetings that were scheduled by clicking the Add Skype meeting button in Outlook on the Web or by using the Skype Meeting add-in for Outlook are migrated. If a user copies and pastes the Skype online meeting information from one meeting to a new meeting, that new meeting won't be updated since there's no meeting in the original service.
  • Meeting content that was created or attached to the meeting (whiteboards, polls, and so on) won't be retained after MMS runs. If your meeting organizers have attached content to the meetings in advance, the content will need to be recreated after MMS runs.
  • The link to the shared meeting notes in the calendar item and also from within the Skype meeting also will be overwritten. Note that the actual meeting notes stored in OneNote will still be there; it's only the link to the shared notes that is overwritten.
  • Meetings with more than 250 attendees (including the organizer) won't be migrated.
  • Some UNICODE characters in the body of the invite might be incorrectly updated to one of the following special characters: ï, ¿, ½, �.

Triggering MMS for a user

This section describes what happens when MMS is triggered in each of the following cases:

  • When a user is migrated from on-premises to the cloud
  • When an admin makes a change to the user’s audio conferencing settings
  • When the user's mode in TeamsUpgradePolicy is set to either TeamsOnly or SfBWithTeamsCollabAndMeetings (using either PowerShell or the Teams Admin Portal)
  • When you use the PowerShell cmdlet, Start-CsExMeetingMigration

Updating meetings when you move an on-premises user to the cloud

This is the most common scenario where MMS helps create a smoother transition for your users. Without meeting migration, existing meetings organized by a user in Skype for Business Server on-premises would no longer work once the user is moved online. Therefore, when you use the on-premises admin tools (either Move-CsUser or the Admin Control Panel) to move a user to the cloud, existing meetings are automatically moved to the cloud and converted to TeamsOnly.

If the user has been assigned an Audio Conferencing license before being moved to the cloud, the meetings will be created with dial-in coordinates. If you move a user from on-premises to the cloud and you intend for that user to use Audio Conferencing, we recommend that you first assign the audio conference before you move the user so that only 1 meeting migration is triggered.

Updating meetings when a user's audio conferencing settings change

In the following cases, MMS will update existing Skype for Business and Microsoft Teams meetings to add, remove, or modify dial-in coordinates:

  • When you assign or remove a Microsoft Audio Conferencing service license to a user, and that user isn't enabled for a third-party audio conferencing provider.
  • When you change the audio conferencing provider of a user from any other provider to Microsoft, provided the user is assigned a Microsoft Audio Conferencing license. For more information, see Assign Microsoft as the audio conferencing provider. Also note that support for third party audio conferencing providers [ACP] is scheduled for end of life on April 1, 2019, as previously announced.
  • When you enable or disable audio conferencing for a user.
  • When you change or reset the conference ID for a user configured to use public meetings.
  • When you move the user to a new audio conferencing bridge.
  • When a phone number from an audio conferencing bridge is unassigned. This is a complex scenario that requires more steps. For more information, see Change the phone numbers on your audio conferencing bridge.

Not all changes to a user's audio conferencing settings trigger MMS. Specifically, the following two changes won't result in MMS updating meetings:

  • When you change the SIP address for the meeting organizer (either their SIP user name or their SIP domain)
  • When you change your organization's meeting URL using the Update-CsTenantMeetingUrl command

Updating meetings when assigning TeamsUpgradePolicy

By default, meeting migration is automatically triggered when a user is granted an instance of TeamsUpgradePolicy with mode=TeamsOnly or mode= SfBWithTeamsCollabAndMeetings. If you don't want to migrate meetings when granting either of these modes, then specify MigrateMeetingsToTeams $false in Grant-CsTeamsUpgradePolicy (if using PowerShell) or uncheck the box to migrate meetings when setting a user's coexistence mode (if using the Teams admin portal).

Also note the following:

  • Meeting migration is only invoked when you grant TeamsUpgradePolicy for a specific user. If you grant TeamsUpgradePolicy with mode=TeamsOnly or mode=SfBWithTeamsCollabAndMeetings on a tenant-wide basis, meeting migration isn't invoked.
  • A user can only be granted TeamsOnly mode if the user is homed online. Users that are homed on-premises must be moved using Move-CsUser as previously described.
  • Granting a mode other than TeamsOnly or SfBWithTeamsCollabAndMeetings doesn't convert existing Teams meetings to Skype for Business meetings.

Trigger Meeting Migration manually via PowerShell cmdlet

In addition to automatic meeting migrations, admins can manually trigger meeting migration for a user by running the cmdlet Start-CsExMeetingMigration. This cmdlet queues a migration request for the specified user. In addition to the required Identity parameter, it takes two optional parameters, SourceMeetingType and TargetMeetingType, which allow you to specify how to migrate meetings:


  • Using TargetMeetingType Current specifies that Skype for Business meetings remain Skype for Business meetings and Teams meetings remain Teams meetings. However audio conferencing coordinates might be changed, and any on-premises Skype for Business meetings would be migrated to Skype for Business Online. This is the default value for TargetMeetingType.
  • Using TargetMeetingType Teams specifies that any existing meeting must be migrated to Teams, regardless of whether the meeting is hosted in Skype for Business online or on-premises, and regardless of whether any audio conferencing updates are required.


  • Using SourceMeetingType SfB indicates that only Skype for Business meetings (whether on-premises or online) should be updated.
  • Using SourceMeetingType Teams indicates that only Teams meetings should be updated.
  • Using SourceMeetingType All indicates that both Skype for Business meetings and Teams meetings should be updated. This is the default value for SourceMeetingType.

The example below shows how to initiate meeting migration for user so that all meetings are migrated to Teams:

Start-CsExMeetingMigration -Identity -TargetMeetingType Teams

Managing MMS

Using Windows PowerShell, you can check the status of ongoing migrations, manually trigger meeting migration, and disable migration altogether.

Check the status of meeting migrations

You use the Get-CsMeetingMigrationStatus cmdlet to check the status of meeting migrations. Below are some examples.

  • To get a summary status of all MMS migrations, run the following command, which provides a tabular view of all migration states:

    Get-CsMeetingMigrationStatus -SummaryOnly
    State      UserCount
    ------     ---------
    Pending      21
    InProgress    6
    Failed        2
    Succeeded   131
  • To get full details of all migrations within a specific time period, use the StartTime and EndTime parameters. For example, the following command will return full details on all migrations that occurred from October 1, 2018 to October 8, 2018.

    Get-CsMeetingMigrationStatus -StartTime "10/1/2018" -EndTime "10/8/2018"
  • To check the status of migration for a specific user, use the Identity parameter. For example, the following command will return the status for the user

    Get-CsMeetingMigrationStatus -Identity

If you see any migrations that have failed, take action to resolve these issues as soon as possible, since people won't be able to dial in to the meetings organized by those users until you resolve them. If Get-CsMeetingMigrationStatus shows any migrations in a failed state, perform these steps:

  1. Determine which users are affected. Run the following command to get the list of affected users, and the specific error that was reported:

    Get-CsMeetingMigrationStatus| Where {$_.State -eq "Failed"}| Format-Table UserPrincipalName, LastMessage
  2. For each affected user, review the value of LastMessage property to determine why the meeting migration failed and what corrective action to take. Once corrective action has been taken, retrigger meeting migration for the affected users, using the Start-CsExMeetingMigration PowerShell cmdlet, as described above.

  3. If migration still doesn't work, you have two options:

The Get-CsMeetingMigrationStatus cmdlet can be used to retrieve status of migrations that were triggered within the past 150 days. Records for migrations older than 150 days are purged from the system.

Enabling and disabling MMS

MMS is enabled by default for all organizations, but it can be disabled as follows:

  • Disable entirely for the tenant.
  • Disable only for changes related to audio conferencing. In this case, MMS will still run when a user is migrated from on-premises to the cloud or when you grant TeamsOnly mode or SfBWithTeamsCollabAndMeetings mode in TeamsUpgradePolicy.

For example, you may want to manually migrate all meetings or temporarily disable MMS while making substantial changes to the audio conferencing settings for your organization.

To see if MMS is enabled for your organization, run the following command. MMS is enabled if the MeetingMigrationEnabled parameter is $true.


If MMS is enabled in the organization and you want to check if it's enabled for audio conferencing updates, check the value of the AutomaticallyMigrateUserMeetings parameter in the output from Get-CsOnlineDialInConferencingTenantSettings. To enable or disable MMS for audio conferencing, use Set-CsOnlineDialInConferencingTenantSettings. For example, to disable MMS for audio conferencing, run the following command:

Set-CsOnlineDialInConferencingTenantSettings  -AutomaticallyMigrateUserMeetings $false

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