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How to enable Lync On-Premise to Federate with Office365 Lync Online

16/04/2011 11 Comments

I’ve just been doing some testing between our Lync On-Premise installation and Office365 Lync Online with Thomas Lee (who is all over Office365 information)

The information about implies that Lync Online, once you choose Open Federation on your web admin console, will federate with any On-Prem Lync installation that also has open federation. We found this not to be the case. Our system is Open federation and already federated to Microsoft (not that that appears relevant), but initially adding contacts didn’t give presence.

Initially no presence


The solution is that you need to add a new Hosting Provider for Lync Online.

By default there are 3 Providers


To add Lync Online either click the new hosting provider,


Or to be quicker launch the Lync Management shell and run the command:

New-CSHostingProvider –identity LyncOnline –ProxyFqdn –Enabled $True


Once you refresh the Lync Control Panel you should see your new hosting provider


Once the CMS has had a minute or two to sync, everything worked fine


Credit where credit is due, I found the solution here

So it seems On-Prem deployments will need to add this hosting provider to allow anyone using Office365 to federate.

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Tom Arbuthnot

Tom Arbuthnot

Principal Solutions Architect at Modality Systems
Tom Arbuthnot is Principal Solutions Architect at Unified Communications specialist Modality Systems. He is a Microsoft Certified Master and MVP, blogger, regular on The UC Architects Podcast, and speaker at events including Microsoft Lync Conference, TechEd and Ignite. He co-runs The Microsoft UC User Group London.
Tom Arbuthnot

Comments (11)

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  1. Thomas F Lee says:

    A great summary of what we found. I am surprised that Office 365 is being treated like PIC rather than just a bunch of domains that happen to be all hosted by MS. I suspect this will cause a bunch of help desk calls to On-Prem users, and probably not a few calls back to MS.

    But it now works and I’m surprised how well it performs – very good for a beta (well so far anyway!). I now have to do a bunch more testing!

    • It is frustrating to me that they require the on-premises installations to take extra steps to federate with the Lync online environment.

      I hope they make changes so that nothing is required for those that use open federation to have to manually add the Office 365 cloud of companies and users when they have already understood the risks associated with open federation.

      We shall see.

  2. Saul says:


    I have done this configuration with a Lync On-Premise and a Lync Online and i have the next problems:

    – Between On-Premise users all functions works, including Internal and External users.
    – Between Online users all functions works.
    – Between On-Premise and Online users IM and the whiteboard works, but I can’t make Video and Audio calls.

    I don’t know if you can help me, is there something I should do on my Firewall?

    Thanks in advance.


    • Does sound like a possible firewall issue.

      Can you take a trace from the front end of a failed call to see what is happening?
      Can you run


    • MH says:

      I have exactly the same issue, can’t make calls from Lync On-premise to Lync Online.
      It works from one On-premises to another.

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