Cisco Cisco Expressway
Microsoft Lync B2BUA interoperating capabilities
When using the Microsoft Lync B2BUA:
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Domain static routes are set up on Lync Server to route calls to domains in the video network.
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Search rules are set up on Expressway to route calls to Lync domains.
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Lync Server accepts and handles call hold (and resume) requests.
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Lync clients can be the object of a transfer (even if there is an AM gateway involved in the call).
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Calls to Microsoft Mediation Servers work from endpoints in the Expressway video network for SIP
initiated calls, but do not work for calls interworked from H.323 (unless the workaround specified in
initiated calls, but do not work for calls interworked from H.323 (unless the workaround specified in
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Lync systems may use hardware load balancers for resilience and capacity.
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A “Lync gateway” Expressway (or Expressway cluster) can communicate to Lync via Lync Director.
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Media encryption (SRTP) is supported when TLS is used between Expressway and Lync and the
Microsoft Interoperability option key is added to the “Lync gateway” Expressway.
Microsoft Interoperability option key is added to the “Lync gateway” Expressway.
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SIP signaling and RTP media is always routed via the B2BUA application for calls involving Lync clients.
Each B2BUA application (one application per Expressway) can handle 100 simultaneous calls between
Lync and the Expressway video environment. However, a call involving Cisco AM GW will consume two
B2BUA call resources.
Each B2BUA application (one application per Expressway) can handle 100 simultaneous calls between
Lync and the Expressway video environment. However, a call involving Cisco AM GW will consume two
B2BUA call resources.
Summary of configuration objectives
This document describes how to configure Lync and the Expressway in B2BUA mode to enable calls from:
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Microsoft Lync clients registered on Lync Server to other Lync clients registered on that Lync Server.
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SIP video endpoints registered to Unified CM in the video network to Lync clients registered on Lync.
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Lync clients registered on Lync Server to video endpoints registered in the video network.
Lync environments
Lync environments have a number of building blocks, and so they may be constructed in many ways. A full
scale Lync deployment is likely to use Lync Director, Hardware Load Balancers (HLBs), Front End
Processors (FEPs) in enterprise pools, and a redundant AD server.
scale Lync deployment is likely to use Lync Director, Hardware Load Balancers (HLBs), Front End
Processors (FEPs) in enterprise pools, and a redundant AD server.
For Lync installations, Microsoft recommend that DNS may be used in place of hardware load balancing for
routing SIP traffic. Microsoft guidance can be found at
routing SIP traffic. Microsoft guidance can be found at
Microsoft Lync and Cisco Expressway Deployment Guide (X8.2)
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Introduction