Tag Archives: Skype for Business Online

Skype for Business Cloud Connector Infrastructure Requirements Part II

This blog post is a 2nd part of my preceding blog post. Part I covers H/W & S/W requirements and basic of DNS, certificates and permissions etc. In this post, I’ll cover the Ports and Protocols requirement for cloud connector edition deployment.

Below illustration shows high level logical deployments scenario with Cloud Connector Edition. Maximum 4 cloud connector can be deployed with one PSTN site. As shown in the diagram, cloud connector edition is deployed in perimeter network. Once you deploy cloud connector edition in perimeter network, required ports and protocol should be open to make it functional.


Below illustration shows the ports and protocol which should be open in internal firewall.

Below illustration shows the minimum ports and protocol which should be open in external firewall.

Below illustration shows the recommended ports and protocol which should be open in external firewall.

This solution will not work if the user end point is behind a symmetric NAT.

For more detailed information, please refer https://technet.microsoft.com/en-us/library/mt605227.aspx

Skype for Business Cloud Connector Infrastructure Requirements Part I

My preceding blog post discuss about different version on Cloud Connector Edition. Cloud connector edition comes with two different versions which support small to large number of calls. Single small version of cloud connector supports 50 simultaneous calls while large version supports 500 simultaneous calls.

3+1 configuration of cloud connectors provide scalability and high availability, 150 simultaneous PSTN calls can be supported in small version and 1500 simultaneous calls in large version.

Both the versions contains 4 VMs and can be downloaded from here.

Hardware requirements to deploy Skype for Business Cloud Connector Edition:


Small Version

Large Version


Intel i7 4790 quad core with Intel 4600 Graphics (no high end graphics needed)

64-bit dual processor, six core (12 real cores), 2.50 gigahertz (GHz) or higher


32 GB DDR3-1600 non ECC

64 gigabytes (GB) ECC RAM


2: 1TB 7200RPM SATA III (6 Gbps) in RAID 0

Four 600 GB (or better) 10K RPM 128M Cache SAS 6Gbps disks, configured in a RAID 5 configuration


2: 1 Gbps Ethernet (RJ45)

Three 1 Gbps RJ45 high throughput network adapters

Host Operating System

Windows Server 2012 R2 Data Center

Windows Server 2012 R2 Data Center




Guest Operating System

Windows Server 2012 R2 Standard / Data Center

Windows Server 2012 R2 Standard / Data Center


Qualified PBX/Trunk or qualified SBC/Gateway (a minimum of two gateways is recommended)

Qualified PBX/Trunk or qualified SBC/Gateway (a minimum of two gateways is recommended)


Apart from all of the above H/W requirements, you have to meet following requirements which are mandatory for Cloud Connector Edition deployment.

Local Server Administrator account for Hyper-V hosts

Domain Administrator information will be asked for new Active Directory to create Domain credential and assign required permissions.

External DNS records will be required for Access Edge per PSTN site and must add all the Edge Servers ip addresses of that particular PSTN site.

Public certificate required for external edge access.

Internet access required for all cloud connectors VM.

Required firewall ports and protocol should be open to execute the cloud connector edition deployment.

Part II of this blog post covers firewall requirements in detail.

Skype for Business Cloud Connector Supported Topology

Skype for Business Cloud Connector is an option for those organizations who have existing telephony infrastructure in-place but not using Skype for Business on-premises or Hybrid infrastructure. With the help of cloud connector customer can opt for Skype for Business Online while they still can leverage their telephony infrastructure for PSTN connectivity.

Let me clarify one thing: Organizations can use either Cloud PBX with PSTN calling service or Skype for Business Hybrid infrastructure to get most/all of the features and functionalities.

Cloud Connector only comes in picture where organizations are not using Lync Server / Skype for Business. When it comes to topology, it again only applicable to Sites which have PSTN infrastructure which needs to be connected with Skype for Business online. Cloud connector edition provides scalability as well as high availability.

Scalability: Multiple instance of cloud connector can be deployed with one or more PSTN sites. Maximum 200 sites can be deployed associated to one Skype for Business online tenant.

High Availability: Up to 4 cloud connector edition can be deployed in 3+1 configuration to provide high availability. In 3+1 configuration, you may get up to 99.8% availability while with 2+2 configuration you may get 99.9% availability.

Cloud Connector comes in two versions:

  1. Small Version (Supports up to 50 simultaneous calls)
  2. Large Version (Supports up to 500 simultaneous calls)

Let me describe multiple supported topologies through illustration:

Single instance of cloud connector with single PSTN site

Multiple instance of cloud connector with single PSTN site

Multiple instance of cloud connector with multiple PSTN sites

As cloud connector is an option for PSTN calls then number of PSTN calls will become a key selective area. Single PSTN site can be configure for up to 150 simultaneous call with small version while large version can support up to 1500 simultaneous calls. If you need more than 1500 simultaneous call in a single site then you can deploy multiple PSTN site in the same location to scale it up.

Skype for Business Cloud Connector Components

This blog post is a continuation of my preceding post “Skype for Business Cloud Connector” and deep dive into the Cloud Connector Edition Components. Cloud Connector Edition deploys a set of VMs which help Skype for Business online to connect and use on-premises telephony infrastructure. It comes with four major components which enable Skype for Business online to talk to the on-premises telephony infrastructure. It encompasses Edge server role components, Mediation server role components, central management store (CMS) and Domain Controller. Let me go in reverse order and explain all of these components.

Domain Controller: It deploys one Domain Controller which is very unique to the respective cloud connector. Let me make it more descriptive; whenever a cloud connector get deploys, it install Active Directory Domain Services and Active Directory Certificate Services. Deployed, ADDS will be part of the new forest and there should not be any connection to the production Active Directory. ADDS is required to store all the global configuration and groups necessary to deploy cloud connector components while ADCS will be installed to generate internal certificates for cloud connector configuration.

Central Management Store: Here CMS consist of two things, CMS role and CMS replica. CMS role store the topology configuration and includes CMS file transfer while CMS replica synchronizes configuration information from the global CMS DB on the CMS role server.

Mediation Server Component: Meditation role components include SIP and other media protocols which are required for PSTN connectivity between Skype for Business and telephony infrastructure. Mediation role also keep and replica of the CMS database which replicates from the global CMS database.

Edge Server Role: Edge server role enables the communication between on-premises topology and the online services which goes through the Edge component. This role consist of following components:

    Access Edge: Enables SIP routing between On-premises topology and Online Services.

    Media Relay: It enables media routing between mediation components and other media endpoints.

    Media Relay Authentication Service (MRAS): It generates tokes to access for media relay.

One more component, outbound routing plays a vital role here. Outbound Routing enables routing to gateways based on policies for outbound PSTN numbers and adhere only global policies.

If you are deploying or integration more than one cloud connector edition in your infrastructure then all the components will be deployed again. Therefore it indicates, all these components are unique to the specific cloud connector.

Skype for Business Cloud Connector

Cloud connector is a unique product from Microsoft which can leverage your existing telephony investment and provide advanced PBX capabilities by using Skype for Business Online and Cloud PBX. SfB cloud connector is an option for those customers who are not using Lync Server 2013 or Skype for Business Server 2015 on-premises infrastructure. Cloud Connector is nothing but a set of VMs which can be deployed on-premises to connect Cloud PBX to implement on-premises PSTN connectivity.

Cloud connector edition deploys a set of VMs which contain a minimal Skype for Business server topology. Each Cloud Connector contains following VMs:

  • Edge Component
  • Mediation Component
  • Central Management Store (CMS)
  • Domain Controller

While planning for Cloud Connector make sure below you considered below points:

  • You should have Office 365 tenant that includes Cloud PBX.
  • You should have existing supported PBX setup running on-premises.
  • All the user will be homed online.
  • You don’t need Skype for Business On-premises deployment but you need virtualized infra to deploy cloud connector. You can’t co-exist cloud connector with on-premises Lync Server 2013 / Skype for Business Server 2015.
  • Cloud Connector is available worldwide.
  • If you want to provide dial-in conferencing to users hosted on Cloud Connector, you can purchase PSTN conferencing from Microsoft or from audio conferencing provider (ACP) partners.


If you have existing Lync Server 2013 / Skype for Business Server 2015 on-premises deployment with telephony setup, then you opt for different options except cloud connector.

Plan your Cloud PBX solution in Skype for Business 2015 or Lync Server 2013

Plan Cloud PBX with on-premises PSTN connectivity in Skype for Business Server 2015 or Lync Server 2013

Skype for Business Cloud PBX

Skype for Business has opened a new era of real time communication with Cloud PBX and Cloud Connector. There are many vendors exist in the market who provide Voice and Video as a service but now with Skype for Business Server, organizations and consumers both will get a new style of collaboration. Skype for Business is an only application which can be fully integrated with other (Microsoft) messaging & collaboration products either on-premises, cloud or in hybrid environment. By using Office Servers and Services (Exchange, Skype for Business, SharePoint & Office 365 etc.), any size of organization can take a full benefit of advanced unified communication and collaboration.

What do you think about Cloud PBX?

Many of us will think about Private Branch Exchange which exist in Microsoft Cloud so that O365 users can make VOIP and PSTN calls. You are correct to some extent, let me explain it.

Cloud PBX is a technology which enables PBX capabilities in the Office 365 cloud which offers Voice over IP within your organization and call control functionalities such as placing, receiving, transferring, muting and unmuting calls etc. With all these functionalities any organization can save opex which occurs in long distance calls. Users can make and receive calls from multiple devices such as desktop/laptop with headset, Lync/SfB phone and mobile device etc. These functionalities could be part of native cloud deployment or in a hybrid environment. Cloud PBX doesn’t mean, users will get PSTN calling services. PSTN calling service is add-on which can be taken on top of Cloud PBX. Below diagram illustrate high level architecture of On-premises, Cloud and Hybrid environment.


Enterprise voice calls can be implemented in two different ways with Cloud PBX:

  1. Organizations can opt for Microsoft PSTN Calling Services.
  2. Organization can integrate Microsoft Cloud PBX with on-premises PSTN infrastructure using Cloud Connector.

Office 365 provides simplify Tenant console for everything including PSTN calling, messaging, collaboration and so on.

Skype for Business online E5 plans cover Cloud PBX while PSTN calling can be taken as an add-on service.

#Skype4B – Hybrid deployment comparison with on premise and online (O365)

In today’s disruptive market Hybrid deployment is a key for any kind of IT infrastructure deployment. Microsoft provides Infrastructure as a service (IaaS), Platform as a service (PaaS) and Software as a service (SaaS) as their cloud offerings. O365 provides SaaS based offerings while Azure provides IaaS and PaaS. O365 offerings provide Exchange Online, Skype for Business Online and SharePoint online. If I talk about wave 15 products such as Exchange 2013, Lync 2013 and SharePoint 2013, I believe you can use full set of features if you have on premise deployment while all these products were tightly integrated with O365.

As we all know, Microsoft is moving and focusing towards mobile-first and cloud-first strategy. Therefore we can see more features are coming for online services and while few of these are not available for on premise deployment. If I discuss about Skype for Business Server 2015 deployment, as of now you can get all the features in on premise deployment except “Broadcast meeting” and “Cloud conferencing recording”. Below is the table which shows high level difference between on premise, online and hybrid deployment. (Courtesy: Microsoft)

As you can see in the above table, hybrid is the only option to get all the features. This is not only for Skype for Business, same thing you can see for Exchange and SharePoint.

Therefore, in short Hybrid is the only way to go.