Resiliency for voice was introduced through Survivable Branch Servers and Appliances starting in Lync Server 2010. This section discusses the various architectures available to organizations planning for voice resiliency.
To revisit the old approach for those performing migrations, back in Office Communications Server 2007 R2 the only way to provide resiliency for a branch site was to leverage dual WAN connections back to the datacenter, or deploy a full redundant set of pool services in the branch. Otherwise, a WAN outage would leave that branch completely offline.
Lync Server 2010 introduced the survivable branch components, which enable a branch to provide a minimal set of services to users in case the connection to the datacenter ...