Have you just started using Lync on Office 365, and when trying to federate with someone on another company, or when they try and federate with you, all you/they see is “Presence Unknown”? Continue reading through all the steps to enable federation on your Lync Online Organization.
The first thing you need to do, is to make sure that all the necessary DNS records are in place. Go to your Office 365 Admin Portal, click on Domains or the left hand side, and you will see all of your domains. Lync uses the UserPrincipalName of the user to set the SIP address, which means that your SIP domain will be the one used for the UPN also (and btw it should also match your primary e-mail address). Select the domain and click on “Manage DNS”.
Make sure the domain purpose is set for Lync Online.
Make sure all the Lync Online DNS records are created on your public DNS zone. You can check which records you need to create also on the Manage DNS section.
Now let’s have a quick look to see if the records are in place. We will check specifically the SIP federation SRV record, but i recommend you check them all. Open a command prompt and run:
nslookup -q=SRV _sipfederationtls._tcp.yourdomain.com
As you can see it points to sipfed.online.lync.com
Now that we know that all the DNS records are in place, go to your Office 365 admin portal and click on “Admin > Lync”
Why is this a required step?
Because the Lync Online Federation comes DISABLED by default
To enable it, on the Lync Online Admin Center, click on “Organization” and on the right hand side, click on the “External Communications” tab.
You will see that the external access is defined to “Off completely”. Change it to “On except for blocked domains” or “On only for allowed domains”. You can also turn on or off the public IM connectivity, and below you can define all the domains to allow or block.
And that’s it, job done. Don’t forget if you just enabled your Lync online tenant you need to allow federation, as it comes disabled by default. And make sure the DNS records are in place!