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The Cloud and Lync Survivability

Migrating to the cloud requires a clear survivability strategy

Alan PercyBy Alan Percy, Senior Director of Marketing, AudioCodes

As businesses examine their options for migrating to Unified Communications with Microsoft Lync, many are looking at cloud-based solutions as a means to reduce capital expenditures and shift to a pay-as-you-go subscription model.  With Lync 2013, there are a number of hosted cloud, dedicated cloud and hybrid cloud options that move the communications solution from the end-customer premise and into the cloud.

However, moving to the cloud does put a significantly greater dependency on the wide area network (WAN), and without a survivability strategy, a simple firewall miss-configuration or network interruption can put even basic voice communications out of service.  Not a good situation for education, banking, financial services and many other vertical markets where voice is critical to continuing operations or the safety of students.

Fortunately, there are purpose-built network elements for Microsoft Lync 2013 that balances the benefits of moving Microsoft Lync to the cloud without sacrificing survivability.

For mid-sized cloud customers or branch sites with between 25 and 1000 seats, Microsoft recommends use of a Survivable Branch Appliance (SBA), a hybrid server/gateway network element that includes a server to host local copies of Lync Server Registrar and Mediation Server along with a local media gateway for access to PSTN circuits.  Ideal for a wide range of deployments and highly popular, SBAs allow mid-size cloud customers to continue business operations in situations when the wide-area network or Lync server pool in the cloud were to be unavailable.

New addition to the survivability solution mix is the Survivable Branch Appliance with Resilient (sometime known as an RBA), which essentially takes the Survivable Branch Appliance and extends its capabilities with WAN resiliency with either redundant wire line WAN connectivity or wireless 4G to facilitate alternate routes for data connectivity, control and messaging while using local PSTN connectivity to carry voice during a WAN outages.   Designed for small offices, RBAs are ideal for retail, financial services, insurance and other businesses that have many small branch offices and a requirement for business continuity during extended network interruptions.

A third option for larger businesses that provides greater functionality during outages is a managed on-site Survivable Branch Server with Enhanced Media Gateway or Enterprise-SBC.  Essentially a complete Lync Server Pool on-site, the Survivable Branch Server offers all the features of IM&P, voice and collaboration during outages.  As a managed offering, cloud customers have the reliability of a full solution while retaining the benefits of a managed cloud subscription business model.

Network Element

Lync Features Retained During Outage

Local PSTN Connectivity

Supports Local
SIP Trunks

Built-in WAN Resiliency

Resilient Branch Appliance (RBA)

Basic call routing + IM and Presence




Survivable Branch Appliance (SBA)

Basic call routing + IM and Presence




Survivable Branch Server + Gateway






Resilient Branch Appliances, Survivable Branch Appliances, Survivable Branch Servers, Enhanced Media Gateways,  Enterprise Session Border Controllers  and other related network elements are all part of AudioCodes’ One Voice for Lync offering, a comprehensive portfolio of voice network elements, a team of highly-experienced professional services and a global support network together from one source.  By teaming with AudioCodes and leveraging One Voice for Lync, partners can be more efficient, win more deals and in the end, be more successful.

To learn more see a demo of these and other advanced Lync deployment architectures, be sure to visit AudioCodes at the upcoming ITExpo in Las Vegas, booth #419 or in the Lync Solution Pavilion at pedestal #412A

You can learn more on the web at:

Continue the conversation with your comments or suggestions - Alan can be reached at

Thumbnail image for Thumbnail image for AudioCodes Gold Competency LogoAudioCodes, a Microsoft Communications Gold Competency partner, designs, develops and sells AudioCodes One Voice for Lync, a comprehensive portfolio of voice networking technology, professional services and global support, optimized for Microsoft Lync and Exchange Unified Communications solutions. Sold through a global network of highly-trained reseller partner community, AudioCodes One Voice for Lync simplifies the selection, implementation and support of Unified Communications. Whether deployed on-premise or in the cloud, AudioCodes is the One Source for Microsoft-certified products and services.  To learn more, visit:

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