Quick Introduction to Skype4B Cloud Connector Edition


With the release of Skype for Business cloud connector edition “CCE”, Microsoft has changed the game and this will encourage more companies to move to Office 365, so let’s talk a little about CCE and what is that?

What is CCE?

CCE is… you can say a new Hybrid way to connect your on premise to office 365. Let’s say that a customer or your organization is using Skype for Business online without PSTN functionalities and without an on premise Skype for Business infrastructure did you pay attention to this 🙂 one more time “and without an on premise Skype for Business infrastructure”, but they do have an on premise PBX infrastructure that allows the users to have PSTN functionalities. with CCE you can now connect your Skype for Business online to your On-premise PBX infrastructure without any additional costs or licenses or the need to have a hybrid deployment with an on premise Skype for Business infrastructure.

CCE is a downloadable package from Microsoft that consist of 4 virtual machines running on Hyper-V, those 4 VMs will be deployed in the organization DMZ connecting the On premise PBX infrastructure to the Skype for Business Online allowing the users to make calls using their SfB clients.

The package that you can download from this link (https://www.microsoft.com/en-us/download/details.aspx?id=51693 ) contains 4 VMs including:

  • Central Management Store
  • Domain controller
  • Mediation Server
  • Edge Server

No it is not stupid and stop freaking out 🙂 , the domain controller is not your company’s domain, and your AD is not going to be on the DMZ, the DC coming in the package has its own forest preconfigured, no connection to your on premise AD is needed, and also it does not affect your Azure AD.

P.S Cloud Connector Edition comes in two versions “Large” or “small”

How does it work?

So this small Topology you will deploy in you DMZ will consist as mentioned before of 4 VMs:

  • Domain Controller:
    • Active Directory services and Active directory Certificate Authority for CCE containing some groups and settings needed by CCE to work.
  • Central Management Store:
    • Consist of two parts:
      • CMS Role: configuration of the topology parts like Edge and Mediation, including File Transfer
      • CMS Replica: replicate configuration from the global CMS DB on the CMS Role server.
  • Edge Server:
    • Consist of the Access, Media Relay, Media Relay Authentication services:
      • Access Edge: used for SIP routing between SfB online and your On-premise PBX
      • Media Relay: routing Media between the Mediation server and the on premise PBX
      • Media Relay Authentication: token for access to media relay
  • Mediation Server:
    • Responsible for SIP signaling and handle the Media

So this would look like this:

One of the good things about CCE is the media travel path, Media does not need to go to Office 365 and come back to the user which would’ve been bad. Only the signaling traffic is traveling through to Office 365 and back to your on premise PBX and out to the provider, once the media is establish, it has two optional paths:

  • Between the user and the PBX via the CCE infrastructure
  • Directly between the user and PBX using Media By-Pass


Media Traverse

After signaling is done, comes the media traffic flow breaking out from the local infrastructure without going through Office 365

Consideration for CCE

  • CCE is not possible for a company with multi-tenant in office 365
  • High Availability achieved by deploying multiple instance of CCE
  • One PSTN site can have up to 4 CCE instances, 3 active and 1 for High availability
  • One large CCE instance support up to 500 concurrent calls, so one site with 3 CCE can support up to 1500 concurrent calls, if more is needed you need to deploy another PSTN site.
  • One small CCE instance support up to 50 concurrent calls, so one site with 3 CCE can support up to 150 concurrent calls, if more is needed you need to deploy another PSTN site or consider deploying large CCE version 🙂
  • Deploy CCE per site to enable local PSTN breakout

Additional information

If you need to get more info regarding planning or deploying CCE I recommend two resources

Author: Lyncdude

A Senior Service Engineer with more than 9 years of experience in Microsoft Exchange and Microsoft Lync Server / Skype for Business. Egyptian guy lives and works in Frankfurt - Germany. what is written in this blog is my own opinion and thoughts, not my employer and does not reflect their opinion

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