skype for business external comminacation


In our organization we use Starleaf Breeze for videoconference. However, we also have Skype for business online as part of our Office365 Enterprise E3 license.

However, when using Skype for business we cannot call external partners. In the Office365 admin center, under Skype for business, we have enabled open federation, but still we cannot call anyone outside our organization.

If i call a test site like with our Starleaf Breeze client, the call is immediately successful. But if i call the same number with Skype for Business, the call just ends in a " was not found"

What am i missing here?
Lars ClausenIT-SupportAsked:
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Lars ClausenIT-SupportAuthor Commented:
As mentioned, i already have enabled open federation
Blue Street TechLast KnightCommented:
If i call a test site like with our Starleaf Breeze client, the call is immediately successful. But if i call the same number with Skype for Business, the call just ends in a " was not found"
If you are actually dialing a third-party entity (not registered as a Skype for Business user) then you'd dial the full phone number not an email address. Is that exact email address registered with an Office 365 tenant and has been assigned the correct licensing and is showing in the Skype for Business Admin center? If not then there would be no way for Skype to know how to communicate with an email address, again, unless it is registered correctly in the Admin center. If it is registered correctly as that exact name for its UPN then follow below.

Are you getting any error messages in the logs?

You need to make sure both tenants have enabled external communication as the article specified above (

Also make sure the firewalls on both sides are not blocking communications.

Here is a decision tree for troubleshooting this exact issue:

This article answers some baseline questions too: .

As a last resort call Microsoft support to resolve - it is included in your plan!

Let me know how it goes!
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Mohammad Ishtyaq khatriSr. EngineerCommented:
what type of licensing your have for skype for business?
Allen FalconCEO & Pragmatic EvangelistCommented:
If you want Skype for Business to be able to dial out during a conference call, or allow users on telephones to dial in, you need add Office 365 Audio Conferencing (formerly call PSTN Conferencing) to those users that need conference call dial-in/dial-out ability.

In the US, the pricing is $4 per user per month.
Lars ClausenIT-SupportAuthor Commented:
i am not looking for a solution where we can use SFB to recieve or make phone calls.
As i mentioned, we only want SFB to be able to call other conference systems outside our organization.

If i look up any video conference test sites, i can call it from or Starleaf system, but our SFB for some reason.
I have tried caling from our coorperate network, my private SDSL (fiber) internet, and a mobile hotspot, but it still dossent work, i therefor asume it is not a firewall issue.

Also, as mentioned, we have our SFB as part of our office365 Enterprise license.
Allen FalconCEO & Pragmatic EvangelistCommented:
Skype for Business can only communicate with others using Skype for Business and Skype clients.  You can allow dial-in and dial out on conferencing with the PSTN add-on.

To communicate with other conferencing systems, you will need to add a gateway/bridging solution.

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Blue Street TechLast KnightCommented:
Lars, any update on this?
Lars ClausenIT-SupportAuthor Commented:
I think what Allan Falcon wrote is the correct answer. I guess SFB cant contact other conference systems without gateway system.
Blue Street TechLast KnightCommented:
You have to provide feedback...that is what we are looking for here...the exchange of information. The more feedback you provide the better the answers you will get! I wrote a ton and you provided no literally response to it. You have to understand we no nothing about your network, setup and many times what the OP actually wants to achieve.

I guess SFB cant contact other conference systems without gateway system.
Yes, conferencing. The conferencing bridge sets your dial-in phone numbers, PINs, and conference IDs for meetings. So you pick which will be the bridge but you can integrate with other conference solutions very easily.


Real Connect by Polycom adds easy interoperability as well:
Lars ClausenIT-SupportAuthor Commented:
Blue Street Tech. Im sorry, but i cant really give you anymore info then i already did.
All i can say is that with our SFB license we can only call other SFB clients, not 3-party conference systems.

All i did was look up a list of test conference sites like

Then i tried calling them with both our SFB and our Starleaf system. Our starleaf can call all of them, our SFB cannot. So as Allan wrote, SFB cannot call other conference systems with the SFB license in our Office365 Enterprise license.
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