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Partners: Planning Lync Survivability

“In the Cloud or On-premise, planning for survivability is key”

By Alan Percy, Senior Director of Marketing, AudioCodes

Microsoft Lync LogoBusinesses of all sizes and types are looking closely at Unified Communications and Microsoft Lync as a means to potentially improve collaboration and reduce telecommunications costs.  As partners, one of the important decisions your customers will make in planning a Lync implementation is deciding on a deployment architecture that best fits their organization.  Helping them make the choice between a traditional on-premise architecture or a cloud-based architecture, the choice includes a number of tradeoffs affecting control, security and survivability.  Irrespective of which architecture the business chooses, remote office and branch office survivability and business continuity needs must be considered in the solution you recommend.  This especially true for cloud-based deployments in which all the business offices will be treated as remote/branch offices

Remote/branch offices come in all sizes and types from simple retail outlets with a few employees to major regional offices with hundreds of employees spanning multiple buildings – one size definitely does not fit all.  Based on the remote/branch office size, there are a few simple recommendations to facilitate survivability:

  • For mid-sized branch offices with between 25 and 1000 seats, Microsoft recommends use of a Survivable Branch Appliance (SBA), a purpose built 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 branch offices to continue business operations in situations when the wide-area network or Lync server pool in the cloud were to be unavailable.
  • For larger remote offices greater than 1000 seats, Microsoft recommends deploying redundant Survivable Branch Appliances or a Survivable Branch Server/Gateway combination.  A Survivable Branch Server is a pre-qualified commercial server platform that would host a local copy of Lync Server Registrar and Mediation Server software.  The general recommendation for local PSTN connectivity is a scalable Enhanced Media Gateway, supporting sufficient T1/E1 or DS3 circuits for the facility.  For remote offices that require full-Lync functionality and business continuity during WAN outages, Microsoft recommends implementing a complete Lync Server Pool on-site, essentially making the remote site an full enterprise-based implementation.
  • For very small offices fewer than 25 seats, a low-cost local Survivable SIP gateway is a good fit, providing only the most basic local PSTN access in cases of a WAN outage or power failure.

A recent addition to the survivability solution mix is the Resilient Branch Appliance (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.

Office # of Seats

Recommended Solution

Lync Features Retained During Outage

Local PSTN Connectivity

Built-in WAN Resiliency

< 15

Resilient Branch Appliance (RBA)

Basic call routing + IM and Presence



< 25

Survivable SIP Gateway





Survivable Branch Appliance (SBA)

Basic call routing



> 1000

Redundant Survivable Branch Appliances (SBAs)

Basic call routing



> 1000

Survivable Branch Server + Gateway




AudioCodes One Voice for Lync LogoResilient Branch Appliances, Survivable Branch Appliances, Survivable Branch Servers, Enhanced Media Gateways,  Survivable SIP Gateways 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.

Microsoft WPC 2013 LogoTo learn about these and other advanced Lync deployment architectures, be sure to visit AudioCodes at the upcoming Microsoft TechEd in New Orleans (booth #410) or at Microsoft World-wide Partner Conference (WPC) during July 7-11th (booth #222) – in either case, requesting an appointment is highly recommended.

You can learn more about Lync Survivability on the web at:

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

AudioCodes Gold Competency Logo

AudioCodes, 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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