Microsoft Lync Server 2010 communications software and Microsoft Office Communications Server 2007 R2 interoperates with AudioCodes Enterprise Session Border Controllers (SBCs) when used with SIP trunking to Internet telephony service providers (ITSPs). This article describes the supported topologies for using Lync Server 2010 or Office Communications Server 2007 R2 with AudioCodes' SBCs.

Author: Wajih Yahyaoui

Publication date: February 2011

Product version: Microsoft Lync Server 2010 and Microsoft Office Communications Server 2007 R2

Lync Server 2010 and Office Communications Server 2007 R2 now support the AudioCodes Enterprise Session Border Controllers (SBCs). Supported topologies are described in this article. AudioCodes and Microsoft partner to regularly test releases of Lync Server and Communications Server, and Microsoft Exchange Server to ensure support of Unified Communications Open Interoperability Program (UCOIP) certified service providers that use the AudioCodes SBCs to connect enterprises into their SIP trunk services. AudioCodes has also joined Microsoft in the Unified Communications Interoperability Forum (UCIF), ucif.org, as a founding member.

While SBC is not required to deploy a SIP trunk for Lync Server and Communications Server 2007 R2, some Internet telephony service providers (ITSPs) may require that you deploy an SBC as an element of your network that is managed and owned by the service provider to connect to their SIP trunk service. This requirement may occur for several reasons, such as the following:

  • Interworking functions The service provider may support only specific signaling and media functions that are not supported by your environment. By deploying a managed SBC, the service provider can resolve these differences.
  • Codecs compatibility The service provider may choose to use a codec other than G.711 or RTAudio. The SBC converts the codec at the perimeter of the customer's network.
  • Quality of service By deploying an SBC within the customer's network perimeter that is managed by the ITSP, the service provider eliminates many of the complexities of interoperating with the customer's systems and can guarantee better service quality.

There are three supported deployment topologies for using the AudioCodes SBCs in conjunction with Lync Server or Communications Server 2007 R2. The first two models involve connecting the Mediation Server directly to an AudioCodes SBC. These deployment models are shown in Figure 1 and 2. Figure 3 illustrates another option. These deployment models are supported only when used for SIP trunk services that have been qualified through UCOIP.

Figure 1 illustrates the Mediation Server connecting directly to the AudioCodes SBC in the ITSP's SIP trunk network infrastructure.

Figure 1. Mediation Server connecting directly to the SBC in the service provider's SIP trunk network infrastructure


Figure 2 illustrates the Mediation Server connected to an AudioCodes SBC that is on customer premises but is managed by the service provider. This SBC is deployed in the customer's network perimeter, which then links the SIP trunk to another SBC in the service provider's SIP trunk network infrastructure.

Figure 2. SBC deployed in the customer's network perimeter

Figure 3 illustrates the SBC connected to the IP-PBX, and the IP-PBX connected to the Mediation Server through Direct SIP. In this topology, SIP trunk connectivity for the Lync Server or Communications Server environment is provided through the enterprise's existing IP-PBX environment (which has an existing SIP trunk to the ITSP). This configuration requires that Direct SIP connectivity is supported for your particular IP-PBX. You can determine whether your IP-PBX is supported by Lync Server or Communications Server 2007 R2 by visiting the UCOIP site.

Figure 3. SBC connected to the IP-PBX

Configuring an SBC for scenarios other than SIP trunk topologies is not supported. For example, configuring an SBC to interconnect to an Edge Server is not supported (Figure 4) because Lync Server and Communications Server clients must connect directly to the Edge Server to maintain the integrity of the end-to-end communication between clients and an Edge Server.

Figure 4. SBC connected to an Edge Server (not supported)

Summary

Microsoft and AudioCodes have collaborated to support direct connectivity deployment models between Microsoft Lync Server, Mediation Server, Communications Server 2007 R2, and AudioCodes Enterprise SBCs.

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Keywords: SIP trunk, telephony, ITSP, SBC, interop,G,711, RTAudio, network, UCOIP,