Exchange Online: Move Mailbox to Exo, don’t forget the Voice Mail

This document outlines the actions that must be taken when a mailbox is migrated to Office 365 to keep the voicemail system running.

When a mailbox is migrated, Unified Messaging, commonly known as cloud voice mail, should be enabled. This activation allows you to benefit from a cloud-hosted mailbox. This mailbox is used by Skype On premise if you receive a call and don’t answer. In this case, the call is forwarded by Skype to the CloudVoicemail service.

How does Skype know that you have a voicemail mailbox hosted on 0365? It’s simple we tell him :

If we take the configuration of my Skype account and look at the details

PS C:\Windows\system32> get-csuser -identity

Identity : CN=TERUIN Laurent,OU=Company,OU=Locations,OU=OU1-France,DC=eu,DC=Ad,DC=net

VoicePolicy :

VoiceRoutingPolicy :

ConferencingPolicy :

PresencePolicy :

DialPlan :

LocationPolicy :

ClientPolicy :

ClientVersionPolicy :

ArchivingPolicy :

ExchangeArchivingPolicy : Uninitialized

PinPolicy :

ExternalAccessPolicy : Allow Federation+Public+Outside Access

MobilityPolicy :

PersistentChatPolicy :

UserServicesPolicy :

CallViaWorkPolicy :

ThirdPartyVideoSystemPolicy :

HostedVoiceMail : True

HostedVoicemailPolicy : CloudUMPolicy

HostingProvider : SRV:

RegistrarPool :

Enabled : True

SipAddress :

LineURI : tel:39876227

EnterpriseVoiceEnabled : True

ExUmEnabled : False

HomeServer : CN=Lc Services,CN=Microsoft,CN=1:69,CN=Pools,CN=RTC Service,CN=Services,CN=Configuration,DC=Ad,DC=net

DisplayName : TERUIN Laurent (External)

SamAccountName : lteruin


You will notice 3 main values which are

  • HostedVoicemailPolicy that indicates that the UM strategy is CloudUmPolicy
  • Exumenabled, : Which specifies that the skype account does not have UM mailboxes on Exchange
  • HostedVoicemail: Which specifies that the hosted mailbox is enabled

If we look at what this famous CloudUMPolicy says we can see that it addresses a cloud service. « Office 365 Voicemail »

PS C:\Windows\system32> Get-CsHostedVoicemailPolicy -Identity CloudUMpolicy

  • Identity: Tag:CloudUMPolicy
  • Description: Office 365 Voicemail
  • Destination:
  • Organization :


This could voice mail service is no longer managed by Exchange UM but by a new service that Microsoft has called « Office 365 Voicemail ».

When you look at the Exchange UM interface on office 365 here is what you get the following message.

The EXUM service is therefore no longer used by Skype on Prem to access the voicemail service now managed by Office 365 Voicemail.

About Cloud Voice Mail

Cloud voicemail offers the following features for both onsite and online users:

  • Voicemail answering and dropping feature with enhanced voice transcription
  • Access to voicemail in the user’s Exchange mailbox using the Skype for Business Online or Outlook clients
  • The ability to use the Office 365 web portal to manage voicemail options
  • Support for Exchange On prem or cloud mailboxes
  • Leverage existing greetings from Exchange Online Unified Messaging users

Impacts and actions to be carried out during the migration of mailboxes to 0365

The migration of user mailboxes will require the following operations for each migration batch

  • Check that all the mailboxes for which you need to activate the cloudvoicemail function are migrated correctly.
  • Verify that users have a license to use Office 365 Voicemail
  • Activate for those with Office 365 Voicemail

The powershell commands to issue are as follows

– Get-CsUser -Identity « User1″ | Grant-CsHostedVoicemailPolicy -Identity  » Tag:CloudUMPolicy »

– Set-CsUser -Identity « User1 » -HostedVoiceMail $True


License O365

In order for the user in question to access and use his CloudVoicemail, he must have a Teams Phone System license or an E5 license.

Default languages for CloudVoicemail announcement messages

The default language of the ads is on our holder, English. It is not possible to change the system language for only one person in the organization. Please note that if the user wishes to change the language of the voice mail announcement, then he can do so via this link.

if the user wants to personalize his voicemail he can do so by following the instructions via the following link;

Announcement and personalization

The system’s default greeting is something like: « Please leave a message for eric Blank. After the tone, please record your message. When you have finished recording, hang up or press the hash key for more options.

Microsoft article:

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