Issue - Microsoft Teams external chat [English/German]

New Contributor

Dear Community,


following problem. I'm not able to contact/chat with external Sfb and Teams Users.

I have allowed external communication in the admin center.

We are in "Teams only".


I can not search for external Users in Microsoft Teams. 

(i have found a workaround, how external Team can contact me - they call me - it rings on my side - and while it is ringig, the other side starts a chat. Then its working. If they try to contact me without this workaround, a chat is started saying "sfb external" -  we are not using sfb anymore - and gets an error that the message could not be sent)


We had an on premise Sfb Server running, which is unactive since 2017. 
This week i have deleted all internal DNS entrys mentioning skype, lync etc.

Our external DNS was updated to:



We only want to use Teams. Exchange is still on premise. Also i have waited 24 hours after changing DNS but still no success.

When i try to verify the DNS - it says that everything seems ok:


To mention: I'm not using any microsoft NS? it that a problem?


I have noticed, that our domain is not set to "standard". The onmicrosoft is currently standard. I wanted to do this, but i get following error:


Saying something like: You can not use a external domain as primary. Choose a different domain and try it again. As mentioned - we are using exchange on prem. Would there be any issue when i set our domain to primary? 


Side Info:

Product License: Office 365 E3
The users all have as Usernames like ""



Also I have noticed, that when i edit a user, the last entry is Skype for Business proberties.

But when i try to follow the link, i receive a blank page

6 Replies

Check through this thread

Is SfB switched on for your users/assigned in the Microsoft 365 Admin Centre? I mean here within their licences? Need this for external communications

Let me know how it goes!

Best, Chris

@Christopher Hoard when i check my user it says that the following license is active:
Office 365 E3
When i expand - it gives me a list of all products. Teams and Skype is active (but it says PLAN 2 on Skype - what does that mean?)



Hi @Danijel_dicom

Thanks for confirming. Assuming you have done everything in this article

If it's still not working then I would raise it to support on a ticket. Would be good to know once the issue is resolved what the root cause of it was to help us in the future.

Hope that answers your question

Best, Chris

Hi @Christopher Hoard 

Support Told me in Azure AD to activate



Onetime via Email for Guestuser. They told to wait 24 hours and then it should work. I'm very sceptical.


Lets see how it goes! Let us know!

Best, Chris

Good morning, 

i have same issues with the switch to Teams Only mode. Microsoft had to adjust the configuration in the backbone.In my tenant, everything was configured correctly. Please open a Microsoft Support case.