Part 6: Polycom RealConnect Interoperability with Skype for Business 2015


This paper will discuss and show how Polycom® RealConnect™ provides a solution for standards compliant H.323/SIP endpoints to interoperate with Microsoft® Skype® for Business 2015 (Lync® 2013) clients. It forms Part 6 of a series that specifically looks at Microsoft Skype for Business 2015 and the challenges and solutions for integrating various H.323 or SIP videoconferencing systems with Skype for Business 2015.

We will show the Polycom RealConnect concept and network topology, then explain the major functions of the RealConnect infrastructure and how these connect with the Skype for Business servers so that you can see how the interactions take place between legacy H.323/SIP endpoints and the Skype for Business 2015 clients. This will explain how this solution overcomes the challenges and how calls are established. Finally, we will discuss the advantages and limitations for this solution as well as its market position.

Within these papers the terms, Lync, Skype, Skype for Business and SfB, unless stated otherwise, all refer to Skype for Business Server 2015. The paper is specifically based on Skype for Business 2015. Whilst Lync 2013 has now been renamed Skype for Business 2015, it is generally backwards compatible with Lync Server 2013.

It is recommended that you look all the papers listed below for a background into Skype for Business and a detailed explanation about the Codecs, Protocols, Procedures and some of the available solutions.


Microsoft Lync is an evolutionary product for Unified Communications (UC). The initial product; Live Communications Server 2003, was only an Instant Messaging (IM) server. This then evolved through several interactions of Live Communications Server to Office Communications Server and then to Lync Server 2010; when a PBX replacement function was added. It then evolved even further to Lync Server 2013 which added much more including video conferencing, web and audio conferencing, softphone and PBX replacement and/or integration. Now, Microsoft have renamed Lync to Skype for Business.

Interoperability for Legacy H.323/SIP Endpoints:

As discussed in other papers, we know that there are basically two methods for integrating Skype for Business with other SIP or H.323 standards compliant videoconferencing systems; namely Native or Gateway.

We also know that for signalling, Skype for Business uses Microsofts implementation of SIP that includes a number of unique extensions and that the video streams use Microsofts implementation of H.264/SVC or its proprietary RTV. Hence, the limitations for native integration are that the endpoint must be able to fully understand Microsofts SIP (MS-SIP) and all the unique extensions; support the Microsoft audio and video codecs, support and use compatible transport protocols and be able to register to the Skype for Business 2015 Server.

But most legacy H.323 and SIP endpoints cannot meet even one of these requirements. Furthermore, there's still the issue that Skype for Business clients use Microsoft proprietary RDP to Application Share, which standards compliant endpoints simply cannot understand.

So how can we solve these issues and provide a solution for legacy H.323 and SIP endpoints?

Polycom RealPresence® Platform:

Polycom have a collection of individual infrastructure products, each of which have a specific function, that collectively make-up what Polycom call the RealPresence® Platform.

The main components of the RealPresence Platform that enable the RealConnect solution are:

  • Polycom RealPresence Collaboration Server (RMX®) appliance
  • Polycom RealPresence Distributed Media Application™ (DMA®) appliance
  • Polycom ContentConnect™ software, virtual appliance
  • Polycom RealPresence Access Director™ (RPAD) appliance
We will look at each component and its function later in this paper.

Polycom RealConnect Concept:

We know that Polycom are currently the only vendor who makes H.323 and SIP compliant videoconferencing endpoints that also support Native Integration with Skype for Business (Lync) Servers; but to address making conference calls that include legacy endpoints which do not support Native Integration, Polycom have developed the RealConnect technology.

Polycom RealConnect offers a solution that allows legacy H.323 and SIP endpoints to full interoperate with Skype for Business 2015 clients including bi-directional Application Sharing (but with a few limitations).

Polycom RealConnect is an umbrella technology that establishes a Gateway to Skype for Business 2015. Basically, Polycom RealConnect is the 'enabling' technology that allows interoperability between the Polycom and Skype for Business 2015 environments directly via their respective network infrastructure as shown in the conceptual diagram below. 

Conceptual diagram showing Polycom RealConnect and how it allows interoperability between the Polycom and Skype for Business 2015 environments directly via their respective network infrastructure

Conference calls between the existing Polycom, H.323 and SIP endpoints look and remain the same. Similarly, conference calls between the existing Skype for Business clients look and remain the same.

What RealConnect does is to enable the Polycom RealPresence Platform to interconnect with the Skype for Business 2015 Servers so that conference calls can seamlessly go between the two different environments. The Polycom RealPresence Platform is a collection of existing Polycom infrastructure products updated to use the RealConnect technology.

Polycom RealConnect Conference Layout:

Central to RealConnect is the Polycom RealPresence Collaboration Server (RMX).

RealConnect uses the RMX to host a Virtual Meeting Room (VMR) in which both environments can participate.

On the Microsoft side, RealConnect technology works in-conjunction with the Front End AVMCU and uses the RMX to provide a Continuous Presence of the VMR into the Skype for Business clients familiar Galley View. Up to 5 of the active Skype for Business 2015 (or Lync 2013) clients are displayed as individual participants as well as the active H.323/SIP endpoint as depicted on the right in the diagram below. 

Diagram showing Polycom RealConnect with RMX hosted Virtual Meeting Room including Skype for Business Clients

On the Polycom side, RealConnect uses the RMX to display the multipoint layout of the VMR. This Continuous Presence layout supports up to 16 participants; these include the H.323/SIP endpoints and up to 5 active Skype for Business clients, as depicted on the left in the diagram above.

Polycom RealConnect with ContentConnect™:

To overcome the issue of bi-directional Application Sharing, RealConnect uses the Polycom ContentConnect in Gateway mode. Polycom ContentConnect is provided as a software package that requires installing on a virtual server.

Polycom ContentConnect in Gateway mode enables a Skype for Business 2015 (Lync 2013, 2010) client or H.323 and SIP standards-based videoconferencing endpoint to share content within a Polycom RealConnect technology meeting.

In this mode, the Polycom ContentConnect operates as a Content Gateway that fully transcodes between the Skype for Business clients Remote Desktop Protocol (RDP) content stream and the SIP videoconferencing endpoints Binary Floor Control Protocol (BFCP) H.264 content stream. Note that any active H.323 endpoints H.239 based H.264 content stream is converted to BFCP H.264 content by the RMX prior to going to the ContentConnect (and vice versa).

Polycom RealConnect and Skype for Business 2015 Topology:

The diagram below shows all the major components, signalling and media paths involved in the RealConnect solution that provides full bi-directional interoperability between Skype for Business (Lync 2013, 2010) clients and H.323/SIP compliant videoconferencing endpoints. 

Network diagram showing RealConnect components with their respective signalling and media streams as well as the Skype for Business 2015 components with their respective signalling and media streams

The RealConnect components are shown along with their respective signalling and media streams. Likewise, the Skype for Business 2015 components are shown along with their respective signalling and media streams.

RealPresence Platform Components & Functions:

Polycom RealPresence Collaboration Server (RMX)

Essentially, the Polycom RealPresence Collaboration Server (RMX) is a high-performance Multipoint Conference Unit (MCU) that breaks down barriers to video collaboration with broad support for existing and emerging standards, protocols, applications, devices and interoperability between unified communications (UC) environments. The Polycom RealPresence Collaboration Server platform provides native integration with Microsofts Skype for Business and support for IP, H.323/SIP, PSTN and ISDN networks within a single appliance.

The Polycom RealPresence Collaboration Server provides support for transcoding between AVC and SVC video protocols without expensive gateways or additional boxes. With the Polycom RealPresence Collaboration Server, dynamic resource allocation provides the right amount of resources per AVC call to reduce costs by eliminating wasted HD resources.

The Polycom RealPresence Collaboration Server integrates tightly with the Polycom RealPresence Distributed Media Application (DMA). Simplified calling, as easy as clicking a link from a calendar or social business application or making a phone call, organisations can intuitively connect over video. Customisable Virtual Meeting Rooms (VMR) now become the conference rooms of the future; used securely and easily by individuals and set up in minutes by to match existing phone extensions - let’s meet at my number' is a great feature.

Polycom RealPresence Distributed Media Application (DMA)

The Polycom RealPresence Distributed Media Application (DMA) offers much more than just being a high-capacity H.323 Gatekeeper and SIP Registrar.

The powerful call processing capability within the Polycom RealPresence DMA allows users to connect regardless of protocol standard, device, network, or location making communication between employees, partners and customers simple, easy and effective. System Administrators can expand and offer new services by leveraging existing communication network investments through the Polycom RealPresence DMA unifying call control application.

The Polycom RealPresence DMA offers a highly resilient and scalable solution that supports any size video network from small deployments of less than 100 devices to an unmatched scale of 25,000 concurrent calls and 75,000 registrations for the largest available networks.

Utilising intelligent algorithms, the powerful software within the RealPresence DMA dynamically routes calls throughout the network based on priority, class of service, resource availability, network outage, and highly efficient load balancing and virtualization of bridging resources.

Polycom RealPresence Access Director (RPAD)

Functionally, the RealPresence Access Director offers a firewall traversal solution to H.323 and SIP endpoints.

The Polycom RealPresence Access Director provides a secure route for users to connect from virtually any location and device, providing support for business-to-business and intra-company collaboration.

The Polycom RealPresence Access Director enables users within and beyond the firewall to securely access video services; whether at home, in the office or on the go. As a software based edge server, the RealPresence Access Director, securely routes communications, management and content through firewalls without requiring additional client hardware or software.

Anybody can securely and transparently access video services and collaborate with colleagues, customers and partners from virtually anywhere, with the same functionality as if they were in the office. Furthermore, customers, partners and vendors can join a video conference as a 'Guest' user or over a federated network. 

For a complete picture, please take a closer look at all the other papers in this series about Skype for Business 2015. 

Polycom® RealPresence® Group Series Administrator Guide v5.0.0, September 2015, 3725-63706-007
Polycom® Unified Communications for Microsoft® Environments - Solutions Deployment Guide, September 2015, 3725-06675-006A