Skype, More Than Just the App

Microsoft bought Skype in 2011 for the weighty sum of $8.5 billion. Many questioned why the Seattle-based company would buy a product that competes with its existing offering (anyone remember Windows Live Messenger?), and whether they would eventually merge into one. The integration of the two can be traced back (officially) to 2013, which leads us to the announcement at the end of 2014 that Lync would be relaunched and rebranded as Skype for Business.

How should I deploy Skype for Business, it’s just an IM (instant messaging) application right? Wrong, Skype for Business is a much bigger fish to fry than most realise. From this point forward in the blog I’m going to abbreviate Skype for Business to SfB to avoid de-railing your train of thought!

SfB is a brand name given to a suite of communication tools and capabilities. In this blog, I hope to walk you through each format SfB solutions can take from a high-level and how to choose between them.

Let’s start with the client app. Much like the consumer tool ‘Skype’ the SfB app is a simple to use, intuitive and covers most of the functionality we need from a collaborative communication tool.

What are the differences between free and business?

There are many, but here are the important ones;


 What’s the difference between plan 1 and plan 2?

SfB is available in two flavours, plan 1 and plan 2. The differences are only relevant if you are purchasing Skype alone, if you’re purchasing something else like 365 E5 then it may include the Skype for Business features you’re after (covered later in this blog). If you are comparing the two stand-alone plans side by side, what are the differences? Well there are a ton of differences which you can view here;

Or you can simply use my simplified table below, I’ve removed anything that matches and left only the differences;


1 The Skype for Business (Lync) client is supported for use with these subscription options, but it is not included. Lync 2013 Basic is available for all customers. The Lync Basic desktop client is a locally installed application that provides presence, instant messaging and conferencing features for Office 365 plans that include Skype for Business Online. Office 365 ProPlus, and Office 365 Enterprise E3 include the full Skype for Business (Lync) application, which include additional features including advanced telephony support, archiving & compliance features. A Skype for Business Online license must be assigned for each user. For more information on Lync Basic features, see Clients for Skype for Business Online

2 A Skype for Business Online Plan 1 user may participate in a sharing session if the user is invited by a Skype for Business Online Plan 2 user.

What’s all the Skype Server stuff about?

Skype as a product from Microsoft is available in PaaS format or ‘Platform as a Service’ and IaaS ‘Infrastructure as a Service’. Up until now this blog has covered the ‘SaaS’ or software as a service options available typically via the Microsoft 365 platform. SfB Server (formerly Office Comms/Lync Server) is a real-time communications software offering that allows an organisation to host secured and controlled unified communications.

With an on-premises server deployment you get the complete UC feature set;

  • Instant messaging & presence
  • Peer-to-peer VoIP and video
  • Audio, video and web conferencing
  • Enterprise Voice and PSTN connectivity
  • Connectivity to others through the Skype network
  • Client and server developer platform
  • Clients available on Android, iOS, Mac, Windows, and web browser

I’ve personally never seen any customer interest in the on premises server solution as the mentality has changed in favour of hosted options in recent years. The only remaining advantages I can think of is that you can control the topology of the deployment, reduce OPEX and you have control over the applied Windows Updates.

Can Skype replace my phone system?

For Skype, this is the ultimate question! In a stereotypical pre-sales response to this, I’m afraid the answer is “well, it depends”. Microsoft have released a couple of deployment options around this, which one suits best is shaped by what your requirements are. Here are the key questions to ask;

  • Do you have an existing on-premises Skype for Business Server deployment?
  • Are your users homed in Skype for Business on-premises, in the cloud on Skype for Business Online, or both? Do you want to move your on-premises users to the cloud?
  • Is Microsoft’s PSTN calling service available in your region?
  • Do you want to keep your current telephony carrier? Do you need to keep your current telephony carrier because of an existing contract?
  • Do you have an existing on-premises legacy PBX that you want or need to keep?
  • Does your current legacy PBX offer unique features that are critical to your business?
  • Do any or all of your users require features not currently offered in Cloud PBX?

This flow chart is used to determine the best course of action;



Follow this link to see what you actually get with Cloud PBX;

Show me Diagrams

I’ve pulled a couple of diagrams from Technet and explained a little bit about each deployment;

PSTN Calling Service

The PSTN service works in tandem with Cloud PBX, the difference is that users can make calls to normal phones not just other Skype clients (such as landlines and mobiles). You don’t need any on-premises server deployments for this solution.


That’s all good but what is PSTN calling?

Cloud Connector

With Cloud Connector you’re basically deploying a hybrid solution using a virtual machine and your existing PSTN service. The virtual machines are downloaded images from Microsoft and communicate between your PSTN and Cloud PBX. There are a couple of different virtual machine server roles required;

  • Edge server
  • Mediation server
  • CMS server – Central Management Store


Cloud Connector enables you to integrate Microsoft Cloud PBX services with your existing telephony environment—for example, PBX, analog devices, and Call Centers—you can implement a phased migration from your existing telephony solution to Microsoft Cloud PBX.

For example, assume your company has a sophisticated Call Center with specific functionality that Microsoft Cloud PBX does not provide. You can choose to leave Call Center users with the existing solution, but move other users to Cloud PBX.

Cloud Connector will provide routing between the users homed on premises and online, and you can choose to use your own PSTN provider with Cloud PBX.

Guide to deploy;

On-premises PSTN connectivity with an existing deployment

Last but certainly not least, another kind-of hybrid solution. This topology enables users to get their PSTN connectivity through Enterprise Voice on your on-premises SfB server deployment. All control of the call routing and configuration is carried out in the cloud.



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