Skype for Business Online SIP URI Define or Change for Office 365 Online User

How is the SIP URI defined in Skype for Business Online?

Can the SIP URI be changed? - Yes!

I ran into an issue today, where we have registered an additional DNS Domain with the customer Office 365 tenant.
Problem was, the UPN and EMAIL address was still

It was necessary changing the SIP address to the new domain.

the User had:

but we need to change actually only the SIP address to

the command
Set-CsUser -identity user -SipAddress
is not working!

ERROR: Unable to set “SipAddress”. This parameter is restricted within Remote Tenant PowerShell.

see support statement:


What is important in Office 365 AZURE AD?

First activation of the tenant defines the default domain as where the UPN of user will be automatically :

Once you add the original domain into the tenant and make it the default domain the user UPN (only those with will be automatically changed too the new default domain with an automated Office 365 internal batch run.

If you define multiple DNS domains, you only one default domain. This default domain is automatically suggested once you create an Office 365 user account.
If you like creating a new user with different UPN/ default domain, change it during the creation task at the top of the create new user wizard (or if via PowerShell, define the DNSdomain there)

Therefore remember the following:

  • UPN (User principal name/ login name) = SIP URI
  • SMTP address can be set different from UPN to any registered DNS tenant domain.

Best Practice is UPN should be equal with the SIP URI and EMAIL address for best user experience)
If a users SIP address should be changed, you MUST change the users UPN.
to the domain/ username you want.

do this graphically within the tenant admin center (users)

B) Use the PowerShell

The user doesn't need to be disabled from any Office 365 service, rather changing the UPN will change the SIP address.
If you need to change the EMAIL/ SMTP address you can use the Admin Center or change it via PowerShell.

This article doesn't fully apply if you af DisSync/ AZURE AD Sync in place.
But the principles still apply in the same way.



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